Matter And Materials Flashcards
What can materials be classified into
Pure substances and impure substance
What can impure substances be classified into
Homogeneous mixtures and heterogenous mixtures
What can pure substances be classified into
Elements and compounds
What can elements be classifieds into
Metals and non metals
Where are metals found on the periodic table
On the left side
Where are non metals found on the periodic table
On the right side
what are the metals in group one called
Alkali metals
What are the metals in group 2 called
Alkali earth metals
what are the group 17 element
Halogen
What are the group 18 elements
Noble gasses
What are some properties of non metals
They are dull, brittle, not sonorous, heat and electrical insulators
What are some qualities of metals
Have lustre, are brittle, are ductile, are sonorous, are heat and electrical conductors
What are electrical cables usually made out of
Copper because it is a good electrical conductor and is relatively inexpensive
What are copper wires usually covered with
plastic because plastic is an insulator
What are heater and stove elements made out of
Nichrome wire because it has high resistance and as a result heat is generated when a electrical current flows through it.
What are cooking pots made out of
Metal because metal is a good conductor of heat. The handles of pots are made out of plastic or other non-metals because they are thermal insulators
what are winter clothes made out of
Thick fabrics which trap air. Air is a thermal insulator, which helps maintain body temperature.
What are magnetic metals called
Ferromagnetic
What are the three magnetic metals
Iron, cobalt and nickel
What are magnets used fo in real life
Electric motors, speakers and compasses
What are semi metals or metalloids
They are elements that have properties of both metals and non metals
What are the 8 metalloids
Boron, silicon, germanium, arsenic , antimony, tellurium, polonium and astatine
Do most metalloids behave like metals or non metals
Non metals
How do metalloids act like non metals
They are brittle
How do metalloids act like metals
They are good conductors of electricity, but not as good as metals
What is an interesting property of metalloids
They conduct electricity better at higher temperature
What are metalloids used in
In microchips
What metalloids are used in microchips
Silicon and germanium.
When is a compound formed
When two or more elements combine chemically in a fixed ratio
What is a mixture
A combination of two or more substances in which each substance retains their individual properties
What are the two types of mixture
Homogenous and heterogenous
What is a homogenous mixture
A mixture in which the composition is the same throughout and consists of two or more substances in the same phase
What is axis a mixture of and what type of mixture is it
Nitrogen, oxygen and small amounts of carbon dioxide. It is a homogenous mixture
What is saline
A homogeneous mixture of water and solid salt
What is a metal alloy
A homogenous mixture of one solid dissolved in another solid
What is an sample of a metal alloy
White gold
What is white gold a mixture of
Gold, palladium, nickel and traces of other metals
What is a heterogenous mixture
A mixture in which the composition is not uniform. You can see the different substances. Any combination of substances that do not dissolve in one another is a heterogenous mixture
What will happen when sand is mixed with water
It will form a suspension. Sand particles do not dissolve in water if left to stand the sand will sink to the bottom
What is it called when two liquids do not mix
They are said to be immiscible
what is an example of an immiscible mixture
Oil and water
What is an example of emulsion
When a mixture of oil and water is shaken and the oil separates into tidy droplets which disperse throughout the water
What can be added to emulsions to prevent them from separating
Emulsifiers
What is mayonnaise
An emulsion of egg yolk and oil
How can mixtures be separated
By physical means
How can a salt water solution be separated by physical means
Through evaporation and condensation
How can oil and water be separated
By using a separating funnel
How can iron filings and sand be separated by physical means
By a magnet
How can water and sand by separated by physical means
Filtration
How can the purity of a substance be checked
By using boiling and melting points
How can purity be checked by using boiling and melting points. Eg. Alcohol and water
Looks like a pure mixture, but can test if it is by seeing if it boils at 100˚c or less. If it is less, the substance is not pure water.
What is another way of checking purity
A process called chromatography
What is chromatography
It is when the substance being tested is dissolved in a liquid such as water. The solution is then passed through another material, such as paper. If the substance is not pure, the different parts travel through the paper at different speeds and are separated
Who was Robert brown
A botanist studying pollen grains suspended in water under a microscope.
What did Robert Brown discover
That minute particles ejected by the pollen were moving around in a random jittery motion.
What is this random motion of the small particles ejected by the pollen grains called
Brownian motion
How did scientists explain this motion
They explained this motion by assuming that all matter is made out of tiny particle, which they called atoms, which are constantly moving
What happens when ink is dropped in water
The ink slowly diffuses into the water, this is done by the movement of the water particles
What determines properties of material
The way the atoms are bonded to one another
What properties does the bonding of atoms determine
Whether a substance is solid, liquid or gas at room temperature
What are the properties of a solid
The particles vibrate in place, strong forces hold the atoms together in a crystal lattice, has its own shape and volume and the particles are close together and not compressible
What are the properties of a liquid
Forces still hold particles together but are weaker than the forces between particles in a solid. particles are able to change place and are therefore able to move over one another and can be poured. It takes on the shape of its container, but has its own volume and the particles are close together and not compressible
What are the properties of a gas
Forces between particle are almost non-existent. Particles are free to move and thus fill the whole container. Has no shape, fills container, fills container, has volume of container. Particles are far apart and are compressible.
What does it mean if all particles are moving but boot at the same speed.
It means that some particles have higher kinetic energy and some have lower kinetic energy
What is temperature
It is proportional to the average kinetic energy of an objects particles
What happens when the temperature of a substance changes
Substances may change phase
What is the melting point
The point at which a solid changes to a liquid
What is the freezing point
The point at which a liquid becomes a solid
What is the boiling point
The point at which a liquid becomes a gas or a gas becomes a liquid
What is evaporation
Not all particles have the same kinetic energy and there are strong forces between the particles. The particles at the top may have more kinetic energy and are able to overcome the force of attraction and escape from the liquid forming a vapour
What happens to the remaining particles once the top layer of the liquid has evaporated
They have less kinetic energy cause the temperature of the remaining liquid to drop. This is used to regulate body temperature
How is evaporation used to regulate body temperature
When we are hot, we sweat, when the sweat evaporates, it cools our body’s down.
What are the similarities between evaporation and boiling
They both result in a phase change from liquid to a vapour
What are the differences between evaporation and boiling
- evaporation takes place at any temperature, boiling takes place at specific temperature.
- Evaporation takes place at the surface only, boiling occurs throughout the liquid
- Boiling takes place when the pressure of the vapour in the bubbles is equal to the atmospheric pressure
What is the relationship between forces and boiling point
The stronger the forces between the particles in a substance are, the higher the boiling point. The weaker the forces between the particles in a substance are, the lower the boiling point. This is because the stronger the forces, the more energy is required to break the bonds between the particles.
What happens when a liquid is boiling
There are bubbles of vapour that form during this process that rise to the top and release their vapour.
How does atmospheric pressure affect boiling point
The boiling point is determined by the atmospheric pressure because a substance will only boil when the pressure in the bubbles in the liquid are the same as the atmospheric pressure. They are directly proportional, the higher the atmospheric pressure, the higher the temperature needs to be for a substance to boil.
What is sublimation
When a substance changes directly from a solid to a gas
What is an example of sublimation
When Iodine crystals are heated, they do not become a liquid by immediately form iodine gas
What happens when a solid is heated
The particle start to vibrate more, thus increasing their kinetic energy, and the bonds between them start to break. The particles also have forces of attraction, and if very close together, they also have forces of repulsion. So in addition to increased kinetic energy, they also have increased potential energy
What happens when a solid is heated to its melting point
The heat does not increase their kinetic energy, but their potential energy. At this temperature the rigid structure of the crystal lattice starts to break apart into the liquid phase only once al the molecules have broken free can they start to gain kinetic energy and the liquid’s temperature starts to rise
What happens when a liquid is heated to its boiling point
The temperature remains constant until all the liquids have been changed into vapours. the heat is converted into potential energy
Why is boiling a substance often more difficult that melting a substance
Because during the boiling, the bonds of the substance have to actually break, whereas when it is melting, they just gain more kinetic and potential energy
What is the current model of the atom
There is a nucleus in the centre of an atom, it consists of protons and neutrons. Electrons orbit around the nucleus
What is the atomic number
The number of protons in an atom. It determines what element it is going to be.
What is the atomic mass of an atom
This is the nucleus because the nucleus is the mass of the atom thus the atomic mass is the protons plus the neutrons
What is an isotope
Atoms of the same element which have different mass numbers. They have the same number of protons, but different number of neutrons
What are the isotopes of chlorine
Chlorine 35 and chlorine 37
What is a cation
A positively charged ion
What is an anion
A negatively charged ion
What is an ion
A charged atom
When is an atom positive
When it has lost electrons
When is an atom negative
When it has gained electrons
What do the names of negative ions usually end with
-ide
What two assumptions did Bohr make
- That electrons can only move in fixed, permitted orbits
- That the electron moving that fixed orbit had a definite energy which could not change while the electron was moving in the specific orbit
What are the fixed energies that electrons in an atom can have called
Energy levels
what can an electron not do while travelling in an energy level
They can not emit energy or absorb energy
How can electrons radiate energy
The electron has to fall from a high energy level to a lower one
How do electrons absorb energy
It has to jump to higher energy levels
What is quantised energy
The energy radiated or absorbed by electrons. It is limited to certain energy values determined by the energy differences between the energy levels
What does the atomic model take into consideration
The wave nature of electrons, which is provided by the fact that streams of electrons produce diffraction patterns
What is it possible to calculate in an atom
The energy, the shape and most likely the position of an electron wave
What are orbitals
The regions where electron waves are most likely to be found.
What are the two orbitals
S-orbital
P-orbital
What is the s-orbital
It is spherical and they are arranged symmetrically around the nucleus, but differ in size.
How many a-orbitals are there in every energy level
Only one
A maximum of how many electrons can be found in the s-orbital
2
The maximum number of electrons that the p-orbital can hold is
6, two in each part of the p-orbital
What is the p-orbital
It is shaped like an infinity sign and comes in groups of 3. They are found in the second energy level onwards. They can hold a total of 6 electrons
What are valance electrons
Electrons found on in the putter most energy level. It is he same as the group numbers
What are the core electrons
They are the electrons found in the inner most energy level
What is the s-block
Groups one and two, this means that the elements found in these groups have their outermost electrons in an s-orbital
What is the p-block
Groups 13 to 18 this means that the elements found in these groups will have their valance electrons in a p-orbital
Groups
Vertical columns
Elements in a group have similar chemical properties
Group numbers enables the charge of an ion to be found
Periods
Horizontal rows
One atom differs from the neighbouring atom by one proton
Period number is = to the number of the outermost energy level
Metals
Are found on the left side
Generally have few valance electrons
Generally lose electrons easily, so they for a positive ion
Non-metals
Right side
Late number of valance electrons
Accept additional electrons, so they form negative ions
Noble gasses
In group 18. They are extremely stable because their outermost energy level is completely full, so they do not bond with other substances
What determines the reactivity of a substance
The presence of unpaired electrons
What happens to atoms during a chemical reaction
They often gain or lose atoms to gain noble gas status.
What are the gradually changing properties of the elements in a given period on a periodic table associate with
With gradually changing valance electron configuration
What is the atomic radius
It is the radius of an atom, from the nucleus to the outermost electrons.
How does the atomic radius change on the periodic table
It decreases from left to right and increases from top to bottom
Why does the atomic radius decrease from left to right
Because the forces of attraction between the nucleus and the electrons increases, cause long the atom to become more compressed
Why does atomic radius increase from top to bottom
Extra energy levels
What is atomic density
The mass per unit volume. This means that it is the size of the atom as well as the in which they are packed together.
Which atoms are more dense
Non-metals because their atoms are not packs as tightly together.
In metals, how does density increase/decrease on the periodic table
From left to right increases
Top to bottom increases
Why does density increase from left to right
Atomic radius decreases and atomic mass increases
Why does density increase from top to bottom
Atomic radius increases, atomic mass increases
What is ionisation energy
The energy required to remove an electron from a single atom in the gaseous phase
How does ionisation energy increase/decrease on the periodic table
It increases from left to right
It decreases from top to bottom
What is electron affinity
The energy liberated when an electron is added to an atom in the gaseous phase
How does electron affinity increase/decrease on the periodic table
It increases from left to right
It decreases from top to bottom
What is electronegativity
It is an indictaion of the attractive force which an atom exerts on a shared electron pair
What is the most electronegative element
Florine
How does electronegativity increase /decrease on the periodic table
The same wa as electron affinity
What are the properties of the alkali metals
Most reactive because they have only one valance electron. Not found in their elementary form in nature, but in compounds. Once the elements have been extracted, they have to be stored in an inert liquid so that they do not react. They all react with cold water to produce hydrogen and a hydroxide. They are all soft and light gray.
What are the properties of the alkali earth metals
They are also very reactive because they only have 2 valance electrons. They all react with cold water, except for beryllium, to produce hydrogen and a hydroxide. All, apart from beryllium, are light grey, relatively soft and are good conductors of heat and electricity
What’s re the properties of the halogens
They are very reactive because they have 7 valance electrons. All have relatively low melting points. At room temperature, Florine and chlorine are gases, bromine is a liquid and iodine and astatine are solids
What are the properties of the noble gases
They are exceptionally unreactive. They are gases at room temperature
What is the bond between two metals called
A metallic bond
What is the bond between two nonmetals called
A covalent bond
What is the bond between a metal and a nonmetal called
An ionic bond
Ionic bond
A transfer of electrons
One is an electron accepter(forms a negative ion) and one is an electron donor (forms a positive ion)
Ions pack in an ionic crystal lattice
What are two important exceptions on the periodic table
Pb and Sn are in group IV but act like tradition metals (2+)
Ag is a transition metal but always has a charge of 1+
Although the transition metals usually have a charge of 2+, many have more that one charge
What are the complex ions with a single charge
NH4^+ H3O^+ OH^- NO3^- NO2^- ClO3^- MnO4^- HCO3^-
What are the complex ions with a couple charge
CO3^2- SO4^2- SO3^2- CrO4^2- Cr2O7^2-
What are the complex ions with a triple charge
PO4^3-
Ammonium
NH4^+
What is hydroxide
OH^-
What is nitrate
NO3^-
What is nitrite
NO2^-
What is chlorite
ClO3^-
What is permanganate
MnO4^-
What is hydrogen carbonate
HCO3^-
What is carbonate
CO^2-
What is sulphate
SO4^2-
What is sulphite
SO3^2-
What is chromate
CrO4^2-
What is dichromate
Cr2O7^2-
What is phosphate
PO4^3-
what does the ending -are represent
A radical containing an oxygen
What does the ending -ite represent
A radical containing one less oxygen than the corresponding -ate radical.
Covalent bonding
Sharing of electrons.
What is a group of covalently bonded atoms
A molecule
What is a molecule
A group of covalently bonded atoms
What is a bonding pair
A shared electron pair
What are lone pair
Pairs of electrons that do not bond
What is a double bond
When there are two bonding pairs
1
Mono
2
Di
3
Tri
4
Tetra
5
Penta
Metallic bonding
Metal atoms loose their valance very easily leaving empty orbitals. Freed electrons able to move sassily from one metal ion to another by the force of attraction between positive ions and the “sea” of negative electrons.
What is the relative formula mass
The relative mass of ionic substances
What is the relative molecular mass
The relative mass of covalent substances
How do you calculate relative mass
Add up the relative atomic masses of each o the elements
What happens to the positive and negative ions that form when electrons are transferred from metal atoms to non-metal atoms
They are attracted to one another and form an ionic crystal lattice
What is the best known example of an ionic crystal lattice
Sodium chloride ( table salt )
What are the properties of ionic compounds
- They are solids at room temperature and have high melting points
- Solid ionic compounds do not conduct electricity but liquid ones can. Most ionic compounds dissolve in water forming and electrolyte solution that will conduct electricity
- they are hard and brittle
Why did ionic compounds have high melting points and whey are they solid at room temperature
Because the forces holding the positive and negative ions together in the crystal lattice are very strong. It thus take a lot of energy to pull ions apart.
Why can solid ionic compounds not conduct electricity
Because the charged particles (ions) are not free to move.
Why can liquid ionic compounds conduct electricity
Because once it is melted, the ions are free to move around and they act as a charge carrier
Why do ionic compounds dissolved in water conduct electricity
Because they dissolve, the ions are free to move
Why are ionic substances hard and brittle
Because when pressure is put on an ionic compound, the layers of ions move and like charged ions line up. The repulsion causes the crystal to break.
What are intramolecular bonds
The covalent bonds holding the atoms in a molecule together. They are strong
When is water a polar molecule
Because the nucleus of the oxygen atom has more protons than hydrogen’s nucleus
What are intermolecular forces
They are the forces holding the molecules together. They are weak forces between a slightly positive side and a slightly negative side of a molecule.
Explain how easy it would be to break he intermolecular and the intramolecular forces in water apart
The intermolecular forces would be easily broken, but the intramolecular forces would be very difficult to break apart.
What do the intermolecular forces between water molecules in the sold phase result it
A tetrahedral arrangement
Why does ice occupy a greater volume than water
Because of the tetrahedral arrangement. Thus the density of ice is less than the density of water.
Why is ice being less fence than water not normal
Because usually, the solid form of a substance is more fence than it’s liquid form
Why is it crucial to the environment that ice is less dense than water
Because in cold parts of the world, when water freezes, it acts as an insulator to the water below, keeping the aquatic life safe.
What would happen if ice behaved like normal compounds
In cold weather, the top layer of water would freeze and sink to the bottom, this would continue to happen until the whole lake was frozen. When warmer weather came, the top layer of ice would melt, and the water would act as an insulator to the ice below
What are the properties of covalent molecular structures
- They have low melting points and are gasses at room temperature
- They do not conduct electricity
- Solid molecular substances are soft
Why do covalent molecular substances have low melting points
Because the intermolecular forces holding the molecules together are weak
What are examples of solid covalent molecular substances that are soft
Iodine crystals and bees wax
What are covalent network structures
They are substances consisting of non-metal atoms covalently bonded to non-metal atoms forming giant molecules
Why are covalent molecular substances so hard to break
Because they have very strong covalent bonds, and thus they have extremely high melting points
What element bonds covalently to form giant molecules
Carbon
What are allotropes
Different crystalline forms of the same element
What are the two allotropes of carbon
Diamond and graphite
How are the carbon atoms in diamond bonded
Each carbon style is covalently bonded to four other carbon atoms forming a giant molecule
What is the meting point of diamond and why is it so high
It is about 3500˚C because the bonds between all the carbon atoms are extremely strong
How are carbon atoms in graphite bonded
They are bonded to each other in layers. Each carbon atom is bonded to 3 other carbon atoms
What are the bonds between the layers of graphite like, and what does this result in
The bonds are weak so the layers can slide over one another. This is why graphite is slippery and can be used as a lubricant.
Why can graphite conduct electricity
Because it has 4 valance electrons, but only 3 are bonded, so the 4th is free to move around
What are the properties of covalent network substances
- Extremely high melting points and are solid at room temperature
- Hard (except graphite)
- Do not conduct electricity (except graphite)
What are the delocalised electrons in metals ions able to do
Move easily from one metal ion to another in the lattice. This forms a lattice of regularly spaced positive ions.
How is the metalic lattice held together
Through the force of attraction between the positive ions and the ‘sea’ of electrons
What are the properties of metallic substances
They conduct heat and electricity
They are malleable and ductile
Have a high density
Have metallic lustre
Why can metal substances conduct heat and electricity
Because the delocalised electrons are free to move
Why are metallic substance malleable and ductile
Because the metal ions and delocalised electrons continues to hold the metal together even under tender conditions
What does it mean that metallic substances have high density
The atoms are packed close to one another
How do metallic substances have metallic lustre
The loosely bound electrons reflect all frequencies of light, this causes the metal to shine
What are the particles in the crystal lattice of a covalent network
Atoms
What are the particles in the crystal lattice of a covalent molecular
Molecules
What are the particles in the crystal lattice of an ionic substance
Positive and negative ions
What are the particles in the crystal lattice of a metallic substance
Positive metal ions
What are the binding forces between particles in a covalent network substance
Covalent bonding
What are the binding forces between particles in a covalent molecular substance
Weak intermolecular forces
What are the binding forces between particles in an ionic substance
Electrostatic forces between positive and negative ions
What are the binding forces between particles in a metallic substance
Forces between ions and delocalised electrons
What is an example of a covalent network substance
Diamond
What is an example of a covalent molecular substance
Dry ice
What is an example of an ionic substance
Sodium chloride
What is an example of a metallic substance
Sodium silver
