C1 Ai Flashcards
What is the approximate radius of an atom?
About 0.1 nanometres (1 × 10^-10 m)
This measurement reflects the scale of atomic dimensions.
What are the components found in the nucleus of an atom?
Protons and neutrons
The nucleus is in the middle of the atom and contains most of the atom’s mass.
What is the radius of the nucleus compared to the atomic radius?
Around 1 × 10^-14 m, approximately 1/100,000 of the atomic radius
This illustrates how small the nucleus is in relation to the entire atom.
What charge does the nucleus of an atom have?
Positive charge
The positive charge is due to the presence of protons.
Where do electrons move within an atom?
In electron shells
Electrons are negatively charged and occupy various energy levels around the nucleus.
What is the relative mass of protons compared to electrons?
Protons are heavy compared to electrons
This mass difference is crucial for understanding atomic structure.
What is the relative mass of neutrons compared to electrons?
Neutrons are heavy compared to electrons
Neutrons also have no charge, contributing to the mass of the atom.
What is the charge of an electron?
Negatively charged
This negative charge plays a key role in chemical bonding.
What does the atomic number of an atom represent?
The number of protons
The atomic number defines the identity of the element.
What is the mass number of an atom?
The number of protons plus the number of neutrons
The mass number gives insight into the total number of nucleons in the nucleus.
In a neutral atom, what is the relationship between protons and electrons?
They are equal in number
This equality results in no overall charge for the atom.
What is an ion?
An atom or group of atoms that has lost or gained electrons
Ions have an overall charge due to the imbalance between protons and electrons.
How do you calculate the number of neutrons in an atom?
Mass number - atomic number
This formula helps determine the neutron count in isotopes.
What is the relationship between atomic number and the number of electrons in an ion with a 2- charge?
Number of electrons = atomic number + 2
This shows that the ion has more electrons than protons.
True or False: Atoms have an overall charge.
False
Atoms are neutral due to equal numbers of protons and electrons.
What is the nuclear symbol for sodium with an atomic mass of 23?
23Na
The symbol indicates both the mass number and the element.
Fill in the blank: The smallest unit of an element is an _______.
atom
Atoms are the fundamental building blocks of matter.
What is a nanometre (nm) in meters?
1 nm = 0.000000001 m
What determines the type of atom?
The number of protons in the nucleus
What is the atomic number of an element?
The number of protons in the nucleus
What do you call atoms with the same number of protons?
Elements
How are atoms of each element represented?
By a one or two letter symbol
What is the symbol for carbon?
C
What is the symbol for sodium?
Na
What are isotopes?
Atoms with the same number of protons but a different number of neutrons
What do isotopes have in common?
The same atomic number
What is the mass number of an atom?
The total number of protons and neutrons
How can relative atomic mass (A_r) be calculated?
Using the formula: A_r = (sum of (isotope abundance x isotope mass number)) / (sum of abundances of all isotopes)
What is the relative atomic mass of copper if Cu-63 has an abundance of 69.2% and Cu-65 has an abundance of 30.8%?
63.6
What is the formula to find the number of neutrons in an atom?
Mass number - Atomic number
True or False: All isotopes of an element have the same mass number.
False
Fill in the blank: Elements are made up of _______.
[atoms]
What is the relationship between atomic number and the element’s identity?
The atomic number defines the element
What is the relative atomic mass of silicon if Si-28 has an abundance of 92.2%, Si-29 has 4.7%, and Si-30 has 3.1%?
Calculated to 1 decimal place
What is the significance of the periodic table?
It displays the symbols of elements
What is the main difference between elements and isotopes?
Elements have different atomic numbers, isotopes have the same atomic number but different mass numbers
What occurs during a chemical reaction?
At least one new substance is made and a change in energy, such as temperature change, can be measured.
What are compounds?
Substances formed from two or more different elements.
How are the atoms of each element arranged in a compound?
In fixed proportions (amounts) held together by chemical bonds.
What is the only way to separate a compound into its elements?
By using a chemical reaction.
What does a chemical equation represent?
It shows the reactants and products in a chemical reaction.
What is a formula in chemistry?
A representation of a compound made up of element symbols in the same proportions as the elements in the compound.
How many atoms of carbon and oxygen are in carbon dioxide (CO₂)?
1 carbon atom and 2 oxygen atoms.
What is the formula for sulfuric acid?
H₂SO₄.
What does the little number outside brackets in a formula indicate?
The number of everything inside the brackets is multiplied by that number.
How many atoms are in calcium hydroxide (Ca(OH)₂)?
1 calcium atom, 2 oxygen atoms, and 2 hydrogen atoms.
Name three compounds and their chemical formulas.
- Carbon dioxide - CO₂
- Ammonia - NH₃
- Water - H₂O
True or False: The formula for sodium chloride is NaCl.
True.
Fill in the blank: The formula for hydrochloric acid is _______.
HCl.
What is the significance of formulas in chemistry?
They show chemical reactions and the composition of compounds.
How many atoms are in one particle of Na₂CO₃?
6 atoms (2 sodium, 1 carbon, 3 oxygen).
What elements are represented in the formula Al₂(SO₄)₃ and how many of each?
- Aluminum - 2 atoms
- Sulfur - 3 atoms
- Oxygen - 12 atoms
What is a word equation in chemistry?
A representation that shows the names of the chemicals reacting and the products formed
Example: methane + oxygen → carbon dioxide + water
What are reactants?
The chemicals on the left-hand side of a chemical equation
They react with each other
What are products?
The chemicals on the right-hand side of a chemical equation
They have been produced from the reactants
What is a symbol equation?
A representation of a chemical reaction that shows the atoms involved on both sides
Example: magnesium + oxygen → magnesium oxide is written as 2Mg + O2 → 2MgO
Why must chemical equations be balanced?
To ensure the same number of atoms on both sides; atoms cannot disappear
Balance by putting numbers in front of the formulas
What is the first step to balance a chemical equation?
Find an element that doesn’t balance and pencil in a number in front of one of the substances
This may need to be adjusted multiple times
What should you never change when balancing an equation?
The chemical formulas
Only the numbers in front of them can be adjusted
What is the balanced equation for the reaction of sulfuric acid with sodium hydroxide?
H2SO4 + 2NaOH → Na2SO4 + 2H2O
Balancing resulted in equal atoms of each element on both sides
Fill in the blank: The chemicals on the left-hand side of a chemical equation are called _______.
reactants
Fill in the blank: The chemicals on the right-hand side of a chemical equation are called _______.
products
True or False: In a balanced equation, the total number of atoms for each element must be the same on both sides.
True
What is the purpose of practicing balancing equations?
To improve speed and accuracy in balancing chemical reactions
Revision is key to mastering this skill
What is an example of a common mistake when balancing equations?
Changing the chemical formulas instead of adjusting the coefficients
Coefficients are the numbers placed in front of compounds
What are mixtures?
Mixtures contain at least two different elements or compounds
How do the components of a mixture interact?
There aren’t any chemical bonds between the different parts of a mixture
What is an example of a gas mixture?
Air is a mixture of gases, mainly nitrogen, oxygen, carbon dioxide, and argon
What is crude oil composed of?
Crude oil is a mixture of different length hydrocarbon molecules
List three methods used to separate mixtures.
- Filtration
- Crystallisation
- Distillation
What are the two types of distillation mentioned?
- Simple distillation
- Fractional distillation
What is chromatography?
A method used to separate components of a mixture
What type of methods are used to separate mixtures?
The methods are all physical methods
Do physical methods of separation involve chemical reactions?
No, they don’t involve any chemical reactions and don’t form any new substances
What do the properties of a mixture represent?
The properties of a mixture are just a mixture of the properties of the separate parts
How does a mixture affect the chemical properties of its components?
The chemical properties of a substance aren’t changed by it being part of a mixture
What is an example of a physical mixture?
A mixture of iron powder and sulfur powder shows the properties of both iron and sulfur
Fill in the blank: A mixture of iron powder and sulfur powder will contain _______ bits of iron and _______ bits of sulfur.
grey magnetic, bright yellow
What analogy is used to describe mixtures?
Think of mixtures like Pick ‘n’ Mix sweets
Give two methods that can be used to separate mixtures.
Filtration and crystallisation
What is chromatography?
A method of separation for items in a mixture.
What is the first step in paper chromatography?
Draw a line near the bottom of a sheet of filter paper.
What should be used to draw the line on filter paper?
Pencil.
Why should a pencil be used instead of a pen?
Pencil marks won’t dissolve in the solvent.
What is a solvent?
A liquid that dissolves another substance.
What should you do after adding a spot of ink to the line?
Pour a small amount of solvent into a beaker to form a shallow layer.
Why might different solvents be used in chromatography?
Some compounds dissolve well in water, while others may require solvents like ethanol.
What should you ensure about the ink spot when placing the paper in the solvent?
The ink shouldn’t touch the solvent.
What is the purpose of placing a lid on the container during chromatography?
To stop the solvent from evaporating.
What is the chromatogram?
A pattern of spots formed by the separated dyes.
What is the solvent front in chromatography?
The point the solvent has reached as it moves up the paper.
How does chromatography separate different dyes in ink?
Each dye moves at a different speed, forming spots in different places.
What happens if any dyes in the ink don’t dissolve in the solvent?
They will stay on the pencil line.
Fill in the blank: Chromatography is useful in real life to test whether athletes have taken _______.
[drugs]
True or False: Chromatography can be used to test things from crime scenes.
True
What is a common application of chromatography mentioned in the text?
Testing for drugs in athletes.
What is the role of the solvent in chromatography?
To carry the ink up the paper.
During chromatography, what does the movement of the solvent indicate?
It indicates how different components of the mixture separate.
What is filtration used for?
To separate insoluble solids from liquids.
Insoluble solids cannot be dissolved in the liquid.
What are the steps involved in the filtration process?
1) Put filter paper in a funnel.
2) Pour the mixture into the filter paper.
3) Ensure the mixture doesn’t exceed the filter paper.
4) The liquid passes through, leaving the solid behind.
The solid is retained in the filter paper.
What is the definition of a soluble solid?
A solid that can be dissolved in a liquid.
Soluble solids can be separated from solutions using evaporation or crystallisation.
What is the first step in the evaporation process?
Slowly heat the solution in an evaporating dish.
The solvent will evaporate during this process.
What happens during the crystallisation process?
1) Gently heat the solution until some solvent evaporates.
2) Stop heating when crystals start to form.
3) Allow the solution to cool for crystals to form.
4) Filter and dry the crystals.
This method is used to obtain large crystals of the salt.
How can you separate rock salt using filtration and crystallisation?
1) Grind the mixture to make salt crystals small.
2) Stir the mixture in water to dissolve salt.
3) Filter the mixture to separate sand from salt solution.
4) Use evaporation or crystallisation to obtain dry salt crystals.
Sand does not dissolve in water, allowing for separation.
What is the purpose of distillation?
To separate liquids based on different boiling points.
This process can be simple or fractional, depending on the complexity of the mixture.
What are the steps in simple distillation?
1) Heat the mixture to evaporate the liquid.
2) The vapor travels to the condenser.
3) The vapor cools and condenses back into liquid.
4) The liquid is collected, while the rest remains in the distillation flask.
This method is effective for separating a solvent from a solute.
What is the difference between simple distillation and fractional distillation?
Simple distillation is used for separating liquids with significantly different boiling points, while fractional distillation separates liquids with closer boiling points.
Fractional distillation involves a fractionating column.
Fill in the blank: ______ separates solids from liquids.
Filtration
True or False: Evaporation can only be used if the salt does not break down when heated.
True
What is the purpose of crystallisation?
To make nice big crystals of a salt
Crystallisation is a method used to separate a solid from a solution.
What is the first step in simple distillation?
The solution is heated
Simple distillation is used to separate a liquid from a solution.
What happens to the part of the solution with the lowest boiling point during simple distillation?
It evaporates first and turns into a gas
This gas then travels into the condenser.
What is the role of the condenser in simple distillation?
To cool the gas and condense it back into a liquid
The liquid then drips out of the condenser.
What is left behind in the flask after distillation?
The rest of the solution
This includes any solids or liquids with higher boiling points.
True or False: Simple distillation can be used to separate mixtures of liquids with similar boiling points.
False
Instead, fractional distillation should be used.
What is fractional distillation used for?
To separate a mixture of liquids
It is effective when different liquids have different boiling points.
What is the main difference between simple distillation and fractional distillation?
Fractional distillation can separate liquids with similar boiling points
Simple distillation cannot.
In fractional distillation, what indicates that a substance has reached its boiling point?
The temperature on the thermometer matches the boiling point of the substance
This allows the substance to rise to the top of the column.
What happens to a substance when it reaches the top of the fractionating column?
It enters the condenser and cools to condense back into a liquid
This liquid can then be collected.
Fill in the blank: To separate a mixture of propanol, methanol, and ethanol, the first liquid to be collected will be ______.
Methanol
Methanol has the lowest boiling point of 65 °C.
What is the boiling point of propanol?
97 °C
This is the highest boiling point among the three liquids mentioned.
What is the boiling point of ethanol?
78 °C
Ethanol is collected after methanol during fractional distillation.
What did scientists originally think atoms were?
Solid spheres.
What model was created after discovering smaller particles within atoms?
Plum pudding model.
In the plum pudding model, how is the atom represented?
As a ball of positive charge with electrons scattered in it.
What type of experiments disproved the plum pudding model?
Alpha particle scattering experiments.
What did scientists expect to happen in the alpha particle scattering experiments?
Most particles to pass straight through with a few changing direction slightly.
What unexpected result occurred during the alpha particle scattering experiments?
Some particles changed direction more than expected, and a few even went backwards.
What model did scientists propose after disproving the plum pudding model?
Nuclear model of the atom.
What are the key features of the nuclear model of the atom?
- A tiny, positively charged nucleus at the center
- Surrounded by a ‘cloud’ of negative electrons
- Most of the mass is in the nucleus
- Most of the atom is empty space.
What did Niels Bohr contribute to atomic theory?
He suggested that electrons orbit the nucleus in fixed shells.
How did Bohr’s theory change the understanding of atom structure?
It introduced the concept of electrons in fixed distance shells from the nucleus.
What particles were discovered in the nucleus after protons?
Neutrons.
Who demonstrated the existence of neutrons?
James Chadwick.
Fill in the blank: The plum pudding model was replaced by the ______ model.
Nuclear.
True or False: The majority of the atom’s mass is located in the electrons.
False.
What does the nuclear model state about the space in an atom?
Most of the atom is empty space.
What is the significance of the experiments that supported Bohr’s theory?
They confirmed the existence of electrons orbiting in shells.
What was the major limitation of the plum pudding model?
It could not explain the results of the alpha particle scattering experiments.
What are electron shells sometimes called?
Energy levels
Which shells are filled up first in an atom?
Inner shells
How many electrons can the first shell hold?
2
How many electrons can the second shell hold?
8
How many electrons can the third shell hold?
8
Why are atoms more stable with full electron shells?
They have full electron shells
What do atoms do if their outer shell is not full?
React to fill it
Fill in the blank: The electronic structure of magnesium is _______.
2, 8, 2
What is the atomic number of magnesium?
12
How many protons does magnesium have?
12
How many total electrons does magnesium have?
12
List the electronic structures of the following elements: H, He, Li, C, Ne, Ca.
- H: 1
- He: 2
- Li: 2, 1
- C: 2, 4
- Ne: 2, 8
- Ca: 2, 8, 8, 2
True or False: The third shell can be completely filled with more than 8 electrons.
False
What is the maximum number of electrons allowed in the third shell?
8
What is the electronic structure of argon (atomic number = 18)?
2, 8, 8
How were elements ordered in the early 1800s?
By atomic weight
What key particles were not discovered until after the early 1800s?
Protons, neutrons, electrons
What did scientists use instead of atomic number to arrange elements?
Atomic weight
True or False: The early periodic tables were complete.
False
What does atomic weight relate to in modern terms?
Atomic mass
What was one issue with arranging elements by atomic weight?
Some elements were placed in the wrong group
Who arranged the known elements into a table in 1869?
Dmitri Mendeleev
What was the primary method Mendeleev used to order elements?
By atomic weight
What did Mendeleev do to ensure elements with similar properties were grouped together?
Switched positions or left gaps
What did Mendeleev predict using the gaps in his periodic table?
Properties of undiscovered elements
True or False: New elements have been found that fit into Mendeleev’s gaps.
True
What are isotopes?
Atoms with different masses but the same properties
Why did Mendeleev swap some elements around in his table?
To keep properties together
Fill in the blank: Mendeleev’s ideas were shown to be ________.
Right
What significant contribution did Mendeleev make to chemistry?
He predicted the properties of elements based on gaps
List two properties of isotopes.
- Different masses
- Same chemical properties
What was a consequence of the early arrangement of elements by atomic weight?
Incomplete periodic tables
What historical significance does Mendeleev’s work represent?
Discoveries building upon discoveries in science
What is the total number of elements in the periodic table?
About 100 elements.
What do the periodic properties of elements give rise to?
The periodic table.
What are the columns in the periodic table called?
Groups.
What does the group number of an element indicate?
The number of outer shell electrons.
How many outer shell electrons does helium have?
Two electrons.
What is a characteristic of elements in the same group?
They react in similar ways.
Give an example of Group 1 elements.
- Li
- Na
- K
- Rb
- Cs
- Fr
What trend is observed in the reactivity of Group 1 elements?
They react more violently as you go down the group.
What are the horizontal rows in the periodic table called?
Periods.
What does each new period represent in the periodic table?
Another shell of electrons.
True or False: Elements with similar properties are not arranged in columns.
False.
Fill in the blank: The pink line in the periodic table separates _______ and non-metals.
metals
What is the relationship between the properties of one element in a group and the properties of other elements in that group?
You can predict the properties of other elements.
What are the two categories of elements typically found in the periodic table?
- Metals
- Non-metals
What are the names of the two groups of elements that are often highlighted in the periodic table?
- Alkali metals
- Halogens
Which elements are considered noble gases?
- Helium
- Neon
- Argon
- Krypton
- Xenon
- Radon
Fill in the blank: The elements in Group 1 have _______ electron in their outer shells.
one
True or False: All elements in a group have a different number of outer shell electrons.
False.
What can you use to help understand the outer shell of an element?
The periodic table.
Suggest a reason why chlorine reacts in a similar way to bromine.
They are in the same group and have similar properties.
What are metals?
Elements that can form positive ions when they react
Metals are located towards the bottom and to the left of the periodic table.
Where are most elements located on the periodic table?
Most elements are metals
Non-metals are found at the far right and top of the periodic table.
How do non-metals typically react?
They don’t usually form positive ions
Non-metals are more likely to share or gain electrons.
What is the significance of a full outer shell in atoms?
Atoms are more stable with a full outer shell
They react by losing, gaining, or sharing electrons.
How do metals typically react to achieve stability?
By losing electrons
This forms positive ions with a full outer shell.
Where are non-metals located on the periodic table?
To the right and towards the top
They gain or share electrons more easily.
What are the physical properties of metals?
Metals are strong, malleable, good conductors of heat and electricity, and have high boiling and melting points
These properties are consistent among all metals.
What are the physical properties of non-metals?
Dull looking, brittle, not always solids at room temperature, poor conductors of electricity, and often lower density
Non-metals exhibit contrasting properties to metals.
Fill in the blank: Iodine usually reacts by forming _______ ions.
negative
State two properties of metals.
Strong, good conductors of heat and electricity
Other properties include malleability and high boiling/melting points.
What are the Group 1 Elements commonly known as?
Alkali metals
What is a key characteristic of alkali metals?
They are reactive, soft metals
How many electrons do alkali metals have in their outer shell?
One electron
What trend occurs in reactivity as you move down Group 1?
Reactivity increases
What happens to melting and boiling points of alkali metals as you move down the group?
They decrease
What is the term used to describe the patterns in properties of elements?
Trends
Fill in the blank: Alkali metals form _______ compounds with non-metals.
Ionic
What do alkali metals produce when they react with water?
A metal hydroxide and hydrogen gas
Write the word equation for the reaction between sodium and water.
Sodium + Water → Sodium Hydroxide + Hydrogen
True or False: The more reactive an alkali metal is, the less violent the reaction with water.
False
What do alkali metals form when they react with chlorine gas?
Metal chlorides
What is produced when Group 1 metals react with oxygen?
Metal oxides
As you go down Group 1, how does the vigor of the reaction with chlorine change?
It gets more vigorous
What happens to the energy released when potassium reacts with water?
It ignites the hydrogen
Fill in the blank: The alkali metals have low _______ and are quite light.
Density
What type of compounds do alkali metals form when they react with non-metals?
Ionic compounds
What is the significance of the little letters in brackets after each substance in a chemical reaction?
They indicate the state of the substance
Why do Group 1 metals have similar properties?
They all have one electron in their outer shell
How were elements ordered in the early 1800s?
By atomic weight
What key particles were not discovered until after the early 1800s?
Protons, neutrons, electrons
What did scientists use instead of atomic number to arrange elements?
Atomic weight
True or False: The early periodic tables were complete.
False
What does atomic weight relate to in modern terms?
Atomic mass
What was one issue with arranging elements by atomic weight?
Some elements were placed in the wrong group
Who arranged the known elements into a table in 1869?
Dmitri Mendeleev
What was the primary method Mendeleev used to order elements?
By atomic weight
What did Mendeleev do to ensure elements with similar properties were grouped together?
Switched positions or left gaps
What did Mendeleev predict using the gaps in his periodic table?
Properties of undiscovered elements
True or False: New elements have been found that fit into Mendeleev’s gaps.
True
What are isotopes?
Atoms with different masses but the same properties
Why did Mendeleev swap some elements around in his table?
To keep properties together
Fill in the blank: Mendeleev’s ideas were shown to be ________.
Right
What significant contribution did Mendeleev make to chemistry?
He predicted the properties of elements based on gaps
List two properties of isotopes.
- Different masses
- Same chemical properties
What was a consequence of the early arrangement of elements by atomic weight?
Incomplete periodic tables
What historical significance does Mendeleev’s work represent?
Discoveries building upon discoveries in science
What are the halogens?
Elements in Group 17 of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine.
What trend can be observed in the boiling points of halogens?
Boiling points increase as you go down the group.
What is the outer shell electron configuration of halogens?
They all have seven electrons in their outer shell.
Define Group 0 elements.
Also known as noble gases, they include helium, neon, argon, krypton, xenon, and radon.
What is the characteristic of noble gases regarding reactivity?
They are unreactive due to having a stable full outer shell.
How many electrons does helium have in its outer shell?
Helium has two electrons in its outer shell.
What happens to the boiling points of noble gases as you go down Group 0?
Boiling points increase.
What is the boiling point of helium?
-269 °C.
True or False: Neon is a gas at 25 °C.
True.
If neon is a gas at 25 °C, what state is helium in at this temperature?
Gas.
Predict the boiling point of xenon if radon has a boiling point of -62 °C and krypton has -153 °C.
Between -62 °C and -153 °C.
What is the actual boiling point of xenon?
-108 °C.
What is a key feature of noble gases in relation to chemical reactions?
They do not form molecules easily and exist as single atoms.
Fill in the blank: The noble gases are ______.
[helium, neon, argon, krypton, xenon, radon].
What is the trend observed regarding the relative atomic masses of noble gases?
They increase as you go down Group 0.
What does an increase in the number of electrons in noble gases lead to?
Stronger forces between atoms.
