Chemistry and Plant Systems Flashcards
Assessment
1
Q
What is the vacuole?
A
The vacuole in plant cells is large and occupies most of the cell. It is filled with sap and stores water, wastes and nutrients. When it is full the vacuole pushes against the cell wall and helps to keep the plant rigid.
2
Q
How are alkali metals different from each other?
A
Moving down group 1, alkali metals become:
Larger, softer and denser
Less heat-resistant, with lower melting and boiling points
And, more reactive.
3
Q
What are molecules and compounds?
A
A molecule is a group of two or more atoms bonded together.
If a molecule consists of:
Only one element, it’s called a molecular element
Or, two or more different elements, it’s called a compound.
H2 and O2 are molecular elements, whilst H2O and CO2 are compounds.
All compounds are molecules, but not all molecules are compounds!
The elements in a compound are always combined in certain fixed proportions. For example, there are always two hydrogen atoms for every one oxygen atom in a water molecule. All of the molecules in a compound are identical.
4
Q
What are the uses of oxygen?
A
It’s used in hospitals for people who struggle to breathe, particularly those with lung disease.
It’s also used by divers and hikers at high altitudes.
5
Q
What are halogens?
A
The halogens are nonmetals found in group 17 of the periodic table.
There are six halogens:
Fluorine (F)
Chlorine (Cl)
Bromine (Br)
Iodine (I)
Astatine (At)
And, tennessine (Ts).
All halogens are one electron short of a full outer electron shell.
6
Q
How are non-metals different across the periodic table?
A
Nonmetallic character increases:
Up a group,
And across a period from left to right.
So, the closer an element is to the top-right corner of the periodic table, the more nonmetallic it is.
7
Q
How are noble gases different from each other?
A
Moving down group 18, the noble gases become:
Larger
And, more heat-resistant, with higher melting and boiling points.
8
Q
What are the rows of the periodic table called?
A
Periods.
9
Q
What is the difference between a molecule and a compound?
A
A molecule is made of two or more atoms bonded together, while a compound consists of molecules that contain two or more different elements.
10
Q
How do we represent elements?
A
Elements are represented by chemical symbols, which are one or two letters long.
Some of these symbols come from the Latin names for elements.
These chemical symbols are universal—allowing scientists to communicate, even if they speak different languages!
11
Q
What are the properties of metals?
A
Solid at room temperature (except mercury)
Usually silver in colour
Lustrous
Malleable
Ductile
Good conductors of heat and electricity
Very reactive
High melting and boiling points
12
Q
Identify which subatomic particle is not found in the nucleus.
A
Electron
13
Q
What are the uses of chlorine?
A
It’s used in household cleaning products and bleach.
Pools are often chlorinated to make them safe to swim in!
14
Q
Describe the male parts on a flower.
A
Flowers have two male parts:
A thin stalk called the filament, attached to the flower.
A small sack called the anther, attached to the top of the filament. The anther contains a fine yellow powder called pollen, which produces sperm cells.
Together, these two male parts are called the stamen.
15
Q
Determine which of the following features all compounds share.
A
Have fixed chemical formulas, Have specific sets of properties, Contain two or more different elements
16
Q
How are electrons arranged?
A
An atom’s electron configuration is the particular way its electrons are organised!
Electrons fill up the innermost electron shell first, which has space for two electrons.
Once the first shell is full, electrons fill up the second shell, which has space for eight electrons.
When the second shell is completely full, electrons fill the third shell, which has space for 18 electrons.
As atoms get bigger in size, they have more electron shells and there are more rules to consider—but we don’t have to worry about this for now!
17
Q
Where are electrons located in an atom?
A
Electrons orbit around the nucleus in energy levels or shells.
18
Q
What are organ systems?
Give example in plants
A
Organ systems are the result of several organs coming together to do even more complex jobs.
The plant organ systems include the:
Shoot system—which is made up of leaves, stems, flowers and fruit
And, the root system—which is made up of all the roots.
19
Q
What is the equation for photosynthesis?
A
Water + Carbon dioxide -> Glucose + Oxygen
20
Q
What are the columns of the periodic table called?
A
Groups
21
Q
Describe the plant structure
A
Flowers are for sexual reproduction. Fruits contain the seeds. Stems are for structure and support. Roots are for anchorage and absorption of water. Leaves photosynthesize and therefore create food for the plant.
22
Q
What are the palisade cells?
A
This layer is tightly packed and contains large numbers of chloroplasts; a large amount of photosynthesis occurs here
23
Q
What are stems?
A
Stems are the organ of a plant that keeps it upright and transports nutrients around the plant.
The stems grow up and spread out above ground.
Stems can come in lots of shapes and sizes.
From the thorny stems on roses to thick tree trunks and winding vines.
24
Q
What do leaves do?
A
Leaves allow plants to breathe—or exchange gases.
They take in carbon dioxide from the air and then release oxygen back into it.
Plant leaves are also used to produce food for plants.
They harness the energy from sunlight to turn carbon dioxide and water into glucose and oxygen.
25
What are the uses of nitrogen?
To preserve packaged foods—when combined with carbon dioxide it helps prevent food from spoiling
And, in the pharmaceutical industry.
26
What is an atom?
All matter is made up of tiny building blocks called atoms.
Atoms are the smallest unit of matter to exist.
They have a radius of about 0.1 nanometres.
Atoms are too small to be seen with the human eye.
Even a powerful microscope can't visualise them!
27
What are plants made of?
All living things are made out of cells.
Not all cells are the same though.
Cells are specialised to do special things to make them exceptionally good at their specific job.
This is why a mango tree has different cells in its fruit—that let it store delicious sugar
Compared to those in its tree trunk—that help keep the tree upright.
28
Describe pollination by insect.
Structure usuall small, some with many flowers in one head, brightly coloured petals especially blues and yellows, small amounts of nectar, strong scent, often strongly marked with landing guides. Often short stamens and smallanthers, close to nectar source in most flowers, sticky pollen. Short style, small stigma close to nectar source. (Insects have poor eyesight, low intelligence, good sense of smell, small bodies.)
29
What are the lower epidermal cells?
Transparent layer of cells on the bottom of the leaf that act like a skin
30
Describe pollination by wind.
Structure is often small but with many flowers in one head, ofte no petals, not brightly coloured, no nectar, no scent. Long stamens with large anthers exposed. Long style with exposed stigma; stigma has large surface area - often look like brushes
31
What holds an atom together?
Opposite charges attract each other.
In an atom, the negative electrons are attracted to the positive nucleus.
This attraction acts like glue to keep the atom together.
The overall charge of an atom is determined by the number of protons and electrons.
When the number of electrons equals the number of protons, each negative charge is balanced by a positive charge.
This means the overall atom has no charge—which we call neutral.
32
What is air space?
Spaces in the leaf where gases move around cells
33
What are roots for?
Roots help to anchor plants into the ground.
This is due to the web-like way that they spread out in the soil.
Roots also help to absorb nutrients from the soil.
Minerals like nitrogen, phosphorus and potassium are absorbed from the soil
And, so is water when it rains.
34
What is the process called when a liquid turns into a gas?
Evaporation or boiling.
35
What makes elements different?
Every element has a different atomic number, which is the unique number of protons in the atoms which make up the element.
Meanwhile, an element's mass number is the number of protons and neutrons in the atom's nucleus.
Along with the chemical symbol, every element's atomic number and mass number can be read off the periodic table.
36
What are isotopes?
All atoms of the same element have the same number of protons.
However, they can have different numbers of neutrons.
Isotopes are atoms of the same element with different numbers of neutrons.
So, isotopes of an element have different atomic masses!
37
What is a chemical formula?
A representation of a molecule showing the elements involved and the number of atoms of each element (e.g., H₂O for water).
38
What are leaves?
Leaves are the organ of a plant that uses photosynthesis to produce the plant's food.
Despite leaves coming in many shapes and sizes, all leaves share a few key features.
Petioles—the short stems that connect the leaves to the plant.
Lamina—the flat green part that catches the sunlight.
Veins—the thin ribs in the leaf that carry nutrients around the leaf and give it structure.
39
What are alkali metals?
Alkali metals are found in group 1 of the periodic table.
There are six alkali metals:
Lithium (Li)
Sodium (Na)
Potassium (K)
Rubidium (Rb)
Caesium (Cs)
And, francium (Fr).
All group 1 elements have one outer shell electron.
40
Label the key information on a tile of the periodic table.
1. Atomic number
2. Chemical symbol
3. Name
4. Atomic mass
41
What are stems made of?
Plant stems are made up of two types of tubes, which together are called the vascular bundle.
Xylem are straw-like tubes that carry water from the roots to the leaves.
These only travel in one direction, from the roots up to the leaves.
Phloem are tubes that carry the sugar produced in the leaves all around the plant.
These travel in both directions, carrying nutrients down the plant and back up again.
42
What structure do noble gases have?
Single atoms
43
What are the properties of non-metals?
Gases or solids at room temperature (except bromine)
Often dull
Brittle
Poor conductors of heat and electricity
Low melting and boiling points
44
What are the uses of aluminium?
Since it doesn't react with air or water, it's used in cans and kitchen utensils.
It can be used as a wrap to cover food because it's malleable!
45
What is a chemical bond?
An attractive force that binds atoms together
46
How are halogens different from each other?
Moving down group 17, halogens become:
Darker in colour
More heat-resistant, with higher melting and boiling points
And, more reactive.
47
What is an ion?
An atom or molecule with a net electrical charge due to the loss or gain of electrons.
48
What is sublimation?
The process of a solid turning directly into a gas.
49
What are mesophyll cells?
Loosely packed cells that give this part of the leaf a spongy appearance
50
What is pollination?
Fertilisation takes place when a male gamete and female gamete join to form a zygote.
While the zygote forms, the ovule forms a seed.
The ovary surrounding the ovule also starts to change into a fruit, which protects and nurtures the zygote.
For these zygotes to become new plants, germination needs to happen.
This requires water, oxygen and the right temperature!
51
What does the cell wall do?
The cell wall keeps the shape of plants and keep it upright.
52
What are the properties of noble gases?
Monatomic gases at room temperature
Chemically inert
Colourless
Odourless
53
What are the upper epidermal cells?
Transparent layer of cells on the top of the leaf that act like a skin
54
What are the properties of metalloids?
Metalloids usually look like metals. They are:
Solid at room temperature
And, lustrous.
Metalloids typically behave like nonmetals. They are:
Brittle
And, average conductors of heat and electricity.
55
What are non-metals?
| list where they are found on table, properties, groups
Nonmetals are elements on the right-hand side of the periodic table that are bad at conducting heat and electricity.
There are two main groups of nonmetals:
Halogens (Group 17)
And, noble gases (Group 18).
All the nonmetals can be found in groups 14–18 in the periodic table.
56
What is the phloem?
Glucose is a molecule created during photosynthesis in the leaves
Glucose is needed as a reactant for cellular respiration which is needed by all cells in the plant
Therefore, glucose must be transported from the leaves to all other parts of the plant
Transportation of glucose in plants occurs in the phloem vessels
Phloem vessels are made up of living cells that join up into long tubes
Transports a glucose mixture (phloem sap) to all parts of the plant
The cell walls that join adjacent phloem cells have perforations (small holes) to allow the phloem sap through
Since glucose is needed in all parts of the plant, the flow of the phloem sap is bidirectional (flows in any direction)
57
Which noble gas is used to preserve important historical documents?
Argon is used to preserve important historical documents. Because argon is not chemically reactive, it creates an inert atmosphere around the document preventing it from decaying or getting damaged.
58
What is the xylem?
Xylem vessels are made from dead cells. When they die, they hollow out into tubes
These tubes carry water and minerals from the soil up to the leaves
Xylem vessels are thickened by lignin which is a woody substance that helps keep the plant upright
The water and minerals move upwards only throughout the plant
Xylem vessels are so thin that water can travel up passively which means no energy used up in the process!
59
60
What is a lattice?
A regular, repeating arrangement of atoms, ions, or molecules in a solid.
61
What are the electrons in an atom?
Electrons orbit the nucleus in defined paths called electron shells.
The attraction between the negative electrons and the positive nucleus acts like super glue to keep the atom together!
62
What is a molecule?
A group of two or more atoms bonded together.
63
Why are elements organised into periods or groups?
Elements in the same period have the same number of electron shells.
The period number tells us how many electron shells the elements have.
This means that elements in the same period are a similar size.
Elements in the same group have the same number of electrons in their outer shell.
For groups 1–2, the group number shows how many electrons are in their outer shell.
For groups 3–12, elements have an inconsistent number of electrons in their outer shell.
For groups 13–18, the last number of the group number shows how many electrons are in their outer shell.
64
What are transport tubes?
The xylem and phloem are vessels that transport different substances in plants
They are grouped together in
vascular bundles separated by a layer of cambium cells
Cambium cells are able to become new xylem or phloem cells as required
Xylem cells are always larger and closer to the middle whereas phloem cells are smaller and on the outer side
65
What is photosynthesis?
Plants make their own food through photosynthesis. In this chemical reaction, chlorophyll in plant cells absorbs light energy to change carbon dioxide and water into glucose and the by-product oxygen.
66
What are the plant pathways?
Water in = xylem
Glucose out = phloem
Carbon dixide in = stomata
Oxygen out = stomata
67
What are the uses of copper?
Electrical cables because it's ductile, malleable and a great electrical conductor.
And, cooking utensils because it conducts heat well!
68
What are the rows and columns in the periodic tabe?
The periodic table is organised into:
Rows called periods
And, columns called groups.
There are seven periods, numbered from top to bottom.
There are eighteen groups, numbered from left to right.
69
What is an atom?
The smallest unit of an element that retains its chemical properties.
70
What are guard cells?
Cells that change the size of the stomatal openings, allowing stomata to open and close
71
What are pollinators?
Pollinators are agents that carry pollen from an anther to a stigma.
These include insects, wind, water, birds and mammals.
We can often tell whether a plant is pollinated by insects or wind just by looking at it!
This is because insect-pollinated flowers need to attract insects and wind-pollinated flowers need to make it easy for wind to pick up and drop off pollen.
72
Why do roots have hair?
Root hairs are long thin tubes that protrude from the surface of a plant's roots
They’re only made from a single cell—and so, are often called root hair cells.
Root hairs are the main site of absorption in the roots.
Root hairs dramatically increase the surface area of the roots
This increases the amount of minerals and water that the roots can absorb.
73
What are metalloids?
They are elements that share properties with metals and nonmetals.
In the periodic table, these elements form a diagonal band between metals and nonmetals.
There are seven semimetals:
Boron (B)
Silicon (Si)
Germanium (Ge)
Arsenic (As)
Antimony (Sb)
Tellurium (Te)
And, Polonium (Po)
74
Recall where most of the mass of an atom is located.
Inside the nucleus
75
How are elements organised in the periodic table?
Increasing atomic number, which is the number of protons in each atom.
76
What is the periodic table?
The periodic table is a way of organising all the chemical elements.
Elements are listed in order of increasing atomic number—from hydrogen at one, to oganesson at 118.
For each element, the periodic table shows its:
Atomic number
Chemical symbol
And, mass number.
77
What is the process of a gas turning into a liquid called?
Condensation.
78
What are noble gases?
The noble gases are nonmetals found in group 18 of the periodic table.
There are seven noble gases:
Helium (He)
Neon (Ne)
Argon (Ar)
Krypton (Kr)
Xenon (Xe)
Radon (Rn)
And, oganesson (Og).
All group 18 elements have full outer electron shells.
79
What makes up a flower?
Flowers are the reproductive organs of flowering plants.
Most flowers contain both male reproductive organs (stamens) and female reproductive organs (carpels).
Stamens are made up of the filament and anther.
Carpels are made up of the ovary and ovules, style and stigma.
80
What is the cuticle?
Waxy waterproof layer that reduces loss of water from the leaf
81
What formulae do we use for molecules and compounds?
The symbols for elements on the periodic table are also used for molecules.
When writing the formula for molecules, we have to indicate the types and numbers of atoms that make up the molecule.
A small subscript number is used to show the number of each atom in a molecule.
Water (H2O) consists of two hydrogen atoms and one oxygen atom.
Carbon dioxide (CO2) consists of one carbon atom and two oxygen atoms.
82
What are the uses of gold?
Jewellery because it's malleable and lustrous.
And, dentistry because it's unreactive.
83
What is relative atomic mass?
The relative atomic mass of an atom is the mass of its nucleus—that is, its protons and neutrons.
Electrons have such a small mass that they're not included in the calculation.
An atom's relative atomic mass can be read off the periodic table along with its atomic number and chemical symbol.
84
Identify what most of an atom's volume is made up of.
Empty space
85
What is the chloroplast?
Plants make their own food from water and carbon dioxide using energy from the Sun. Photosynthesis takes place in chloroplasts, which are found in the green parts of plants.
Plant cells in the upper surface of leaves have chloroplasts which contain the green pigment called chlorophyll. It is chlorophyll which absrbs light enegy from the Sun, that enables plants to carry out photosynthesis.
86
Describe pollination by mammal.
Large strong flower heads, often not brightly coloured in many and often hidden in plant , much nectar produced at night. Anthers, stamens, stigmas all strong and rigid. (Mammals have good eyesight, intelligent, most are nocturnal, good sense of smell, large bodies.)
87
Where are protons and neutrons located in an atom?
In the nucleus at the centre of the atom.
88
Describe petals and sepals.
Petals come in almost every colour and can smell delightful. Their role is to attract birds, bats, bees and other insects to the flower. These organisms help the plant reproduce.
Before a flower blooms, it can look like a green bud. The protective green petal-like structures are called sepals. Once the flower blooms, the sepals can remain green or change colour.
To tell the sepals from the petals, all you have to do is smell them. The sepals do not have a scent.
89
Label a flower:
Stigma, style, ovary = Pistil/Carpel
Anther, filament = Stamen
Petals, sepals
90
What is the equation for respiration?
Glucose + Oxygen -> Water + Carbon dioxide
91
Explain why noble gases are chemically inert.
Noble gases are chemically inert which means they are stable and not chemically reactive. This is because they have a full outer electron shell so they don't accept or donate electrons.
92
What are halogens used for?
Fluorine is used in toothpaste and plastics.
Chlorine is used in swimming pool disinfectants.
Bromine is used in agricultural chemicals, insecticides and film photography.
Iodine is used in wound antiseptics.
93
What is the structure of an atom?
The structure of an atom can be represented using a simple model.
The nucleus of an atom consists of protons and neutrons.
Electrons orbit around the nucleus in shells.
This orbit is much bigger than the nucleus itself!
With more protons, neutrons and electrons, the atom gets bigger in size.
94
What are roots?
Roots are the structure of plants that attach them to the ground and absorb nutrients from the soil.
Roots can be divided into three major parts.
Primary roots (taproot)—this is the main root, which grows straight down from the plant
Lateral roots—these are the roots that branch off the primary root.
And, the root hairs—these are fibrous structures that cover the lateral roots.
95
When does the atom have an overall charge of zero and is said to be neutral?
If there is an equal number of protons and electrons then the positive and negative charges balance each other out. The atom has an overall charge of zero and is said to be neutral.
96
What are metalloids used for?
Silicon is used in electronics and rubber.
Boron is used in borosilicate glass and household cleaners.
Antimony is used in coloured paints and enamels.
97
What are leaves made of?
Plant leaves have a few structures to help them exchange gases and produce food.
Stomata are tiny holes under leaves where they exchange carbon dioxide and oxygen.
Guard cells sit on either side of the stomata to open and close them.
Chloroplasts are structures in leaves that make them green!
They're also where photosynthesis happens.
98
What are elements?
Elements are made up of only one type of atom.
About 90 elements exist naturally on Earth. The rest are all man-made and reactive.
99
What are the properties of alkali metals?
Soft
Low density
Very high reactivity
Low melting and boiling points
100
How are elements classified in the periodic table?
Elements which have similar properties are grouped together in the periodic table.
The periodic table can be split into three different types of elements:
Metals
Nonmetals
And, metalloids.
101
What are metals?
Metals are elements on the left-hand side of the periodic table that are good at conducting heat and electricity.
There are three main groups of metals:
Alkali metals (Group 1),
Alkaline earth metals (Group 2),
And, transition metals (Groups 3–12), which include: actinides and lanthanides.
102
What are subatomic particles?
Atoms are made up of subatomic particles—protons, electrons and neutrons.
Protons are positively charged,
Electrons are negatively charged,
And, neutrons are neutral.
Electrons are smaller and have less mass than protons and neutrons, which are a similar size.
In a neutral atom, the total number of electrons is equal to the total number of protons.
This means that the atom has no overall charge.
103
Describe the female parts of a flower.
There are three female parts:
The small tip that sticks out of the flower to collect pollen is called the stigma.
The stigma is attached to a long tube that transports pollen. This is called the style.
The style moves pollen from the stigma to a round section at the base of the flower. This is the ovary. Just like in humans, the ovary contains eggs. These are the female sex cells. When male sex cells in the pollen reach the eggs, they combine to form seeds.
The stigma, style and ovary are together called the pistil.
104
What do stems do?
Plant stems keep plants upright, sort of like our skeleton.
They start at the base of the plant, where they’re thickest, to hold up the whole plant
And, they stretch up into the air, branching out and getting thinner.
Plant stems connect all the different organs together, so they can exchange nutrients.
Minerals and water absorbed in the roots can be sent up the plant
And, sugars made in the leaves can be sent down the plant.
105
What are leaves?
Gas exchange primarily occurs in the leaves
Leaves are flat and thin to maximize the surface area exposed to sunlight to make photosynthesis more efficient
Epidermis and cuticle are transparent to allow sunlight to come through
Mesophyll cells (palisade + spongy) contain many chloroplasts as their function is to photosynthesize
106
What are the three main subatomic particles in an atom?
Protons, neutrons, and electrons.
107
What are some common molecules and compounds?
Some common molecular elements are:
Oxygen (O2)
Nitrogen (N2)
Hydrogen (H2)
Chlorine (Cl2)
And, ozone (O3).
Some common compounds are:
Carbon dioxide (CO2)
Water (H2O)
Methane (CH4)
Acetic acid (CH3COOH), the main component in vinegar
And, nitrous oxide (N2O), also known as laughing gas.
108
Examples of compounds and their uses:
Sodium chloride (NaCl) is used to season foods and as a preservative.
Carbon dioxide (CO2) is used to make soft drinks 'fizzy'.
Sulfuric acid (H2SO4) is used to make fertilisers, medicines, batteries, detergents, paints and inks!
109
What are organs?
When groups of similar cells group together to do a similar job, they form tissue.
Plants have different kinds of tissues.
In a plant stem, there is dermal tissue, vascular tissue and ground tissue.
Organs are the result of several types of tissue coming together.
Organs combine all the functions of the tissues, to do an even more complex job.
Plants have lots of organs, like their stems, roots and leaves.
110
What are the properties of halogens?
Diatomic molecules in nature
Very high reactivity
Brittle when solid
Poor conductors of heat and electricity
Low melting and boiling points
111
How do plants reproduce?
Pollination occurs when pollen grains are transferred from an anther to a stigma.
On top of the stigma, one of the cells in the pollen grain will tunnel down into the stigma to reach the ovules.
There are a couple of different types of pollination: self-pollination and cross-pollination.
Self-pollination is when pollen lands on the stigma of the same flower or same plant.
Cross-pollination is when the pollen from the flower of one plant lands on the stigma of the flower of another plant.
112
What are noble gases used for?
Helium is used in balloons and scuba diving tanks.
Neon is used in neon signs.
Argon is used in some light bulbs and the preservation of paper documents.
113
Describe pollination by bird
Large strong flowers, some ahve petals but my don't, lots of nectar, often red. Often long, strong stamens and large anthers, sited a long way from the nectar source. Long style, smallish stigma, sited a long way from the nectar source. (Birds have good eyesight, intelligent, most active in daylight, poor sense of smell, large bodies.)
114
What is the stomata?
Leaves have many microscopic pores called stomata on them where the gases are exchanged. (Carbon dioxide)
They are mainly located on the underside of the leaf - to prevent water loss.
There are spaces in between the mesophyll cells to allow for the gases to move freely in to move in, out and around mesophyll cells.
Stomata are surrounded by two bean-shaped guard cells that are can open or close the pore when necessary
When the stomata are open, the plant loses lots of water through transpiration (evaporation of water)
Therefore, the stomata often close when the sun is strongest because the plant needs to conserve water
The stomata remain open when the plant has enough water available to it and the sunlight is moderate
115
What charge do protons, neutrons, and electrons have?
Protons are positively charged, neutrons have no charge, and electrons are negatively charged.
116
How are metals different across the periodic table?
Metallic character increases: down a group and, across a period from right to left.
117
What is a chemical element?
A substance made up of only one type of atom
118
How does water move up a plant?
Water evaporates through the stomata (transpiration)
Water molecules stick to the walls of the xylem (capillary action)
Since water is being lost through the leaves, it creates a tension force on the water, pulling it upwards
Since there is a strong attraction force holding water molecules together (cohesion), the body of water moves up as one ‘piece’
All these forces allow water to move up the tree passively!
(no energy cost for the plant)
However, a push force at the roots is often necessary to start the process
This push force is active, meaning it costs the plant some energy
119
Select the option that best completes the following sentence.
Chemical bonds are attractive forces between:
Atoms in both lattices and molecules
120
How can compounds be arranged?
Molecules or lattices
121
Compare compounds and mixtures
Compounds are made up of two or more types of atoms (chemically bonded), with fixed proportions, and cannot be physically separated.
Mixtures are not chemically bonded, not in fixed proportions but can be physically separated.
122
Define "reactants"
The substances that react with each other in a chemical reaction
123
Define "Products"
The new substances formed by a reaction.
124
Why are compounds pure substances?
Nomatter which atom arranement you have in a compound, you can never physically divide it into different substances.
125
Describe the chemical bonds in molecular compounds
The bonds within the molecules are too strong to break physically, so you can't separate the different elements.
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What is a homogeneous mixture.
Mixtures with a constant composition - all parts look the same
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What are atoms?
Smallest part of an element that can take part in a chemical reaction. They represent the simplest form of matter.
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What is a molecule?
Smallest part of a substance that can exist independently. Molecules form when two ormore atoms chemically bond together. These atoms may be identical to each other or different.
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What are elements?
Made up of one typeof atom only. Therefore matter which we classify as an element can exist as single atoms or as molecules provided the atoms in the molecule are all the same.
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What are compounds?
Contain at least two diferent atoms bonded together. Compounds can therefore only be molecules as there must be at least two atoms in the particle.
