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What is melting?
When a solid changes into a liquid
What is boiling?
When a liquid changes into a gas (from below surface as well as at surface)
What is freezing?
When a liquid changes into a solid
What is evaporation?
When a liquid changes into a gas (at surface only)
What is condensation?
When a gas changes into a liquid
What is sublimation?
When a solid changes directly into a gas
What is deposition?
When a gas changes into a solid
What are intermolecular forces?
Forces between molecules
What is a solution?
The mixture formed when a solute has dissolved in a solvent
What is a solute?
Substance being dissolved
What is a solvent?
Substance where the solute is dissolved
What is a saturated solution?
A solution that contains the maximum amount of dissolved solute
What is a soluble substance?
A substance that dissolves in a solvent
What is an insoluble substance?
A substance that can't be dissolved
What is diffusion?
Net movement of particles from areas of high concentration to areas of low concentration
What is dilution?
Mixing a substance with a solvent to make it less concentrated
What is Brownian motion?
When particles in fluids move randomly because they are bombarded by other moving particles
What is a homogeneous mixture?
A mixture in which the composition is uniform throughout
Why doesn't diffusion happen in solids?
Because the particles don't move
What are isotopes?
Atoms of the same element with different numbers of neutrons
What does the group number tell you?
How many electrons are in the outer shell
What does the period number tell you?
Number of shells
Why do atoms want a full outer shell?
So they can become more stable
What is ionic bonding?
Transfer of electrons between a metal and a non-metal
What is electrostatic attraction?
Attraction between opposite charges
What happens when an atom loses an electron?
It becomes a positive ion because it loses a negative charge
What is a covalent bonding?
when atoms share one or more pairs of electrons
What is simple distillation?
Used for separating a liquid from a solution
What is fractional distillation?
A technique for separation of a mixture of liquids that have different boiling points
What does miscible mean?
Two liquids which can mix together
What is filtration?
Used to separate an insoluble solid from a liquid
What is crystallisation?
Separates a soluble solid in a solvent from a solvent
What is chromatography?
Used to separate a mixture of substances dissolved in a solvent
Why is the line drawn in pencil in chromatography?
Pencil is insoluble and will not dissolve in the solvent
Why are group 1 metals so reactive?
Because they only have one electron in their outer shell
What are group 1 atoms known as?
The alkali metals
What are group 7 atoms known as?
The halogens
Why does bonding occur?
To make atoms stable
What is an element?
A substance that contains only one type of atom
What is a compound?
2 or more elements chemically combined
What is a mixture?
Two or more elements or compounds not chemically combined together
What is a molecule?
2 or more atoms bonded together
What does the amount of energy needed to change state from solid to liquid or liquid to gas depend on?
The strength of the forces between the particles of the substance
Ammonium
NH₄⁺
Hydroxide
OH⁻
Carbonate
CO₃²⁻
Nitrate
NO₃⁻
Sulfate
SO₄²⁻
What is the structure of an ionic compound?
Giant ionic lattice
Why do ionic compounds have high melting and boiling points?
Due to the strong electrostatic forces of attraction between oppositely charged ions
In what state do ionic compounds conduct electricity?
Liquid state
What is an atom?
Ana atom is the smallest unit of matter
What is an RF value?
The ratio of the solute's distance travelled to the solvent's distance travelled
What is relative atomic mass?
Average of the mass numbers of the different isotopes
What is abundance?
Relative amount of each isotope
What is the mass number?
Number of protons and neutrons
What is an electron?
A negatively charged subatomic particle
What is the difference between boiling and evaporation?
Boiling affects the whole liquid while evaporation only affects the surface
What is solubility?
A measurement of how much a substance will dissolve in a given volume of a liquid
What is an ion?
An atom that is charged because it has lost or gained and electron
What is the difference between ionic and covalent bonding?
Covalent bonding refers to the sharing of electrons while ionic bonding is the complete transfer of electrons
What is matter?
Anything that has mass and takes up space
How does molecular mass affect the rate of diffusion?
Heavier molecules move more slowly; therefore, they diffuse more slowly
Hydrogen
H⁺
What is a diatomic molecule?
A molecule consisting of two atoms
What is the arrangement of particles in a solid?
They are close together in a regular pattern
What is the arrangement of particles in a liquid?
They are close together in a random pattern
What is the arrangement of particles in a gas?
They are far apart and in a random pattern
What is the movement of particles in a solid?
Vibrate around a fixed position
What is the movement of particles in a liquid?
Flow past each other
What is the movement of particles in a gas?
Move quickly in all directions
Describe the energy of particles in a solid
Low energy
Describe the energy of particles in a liquid
Medium
Describe the energy of particles in a gas
High
How do can you distinguish purity in substances?
Pure substances melt and boil at specific and sharp temperatures e.g. pure water has a boiling point of 100 °C and a melting point of 0 °C
Why do mixtures have a range of melting and boiling points?
They consist of different substances that tend to lower the melting point and broaden the melting point range
What is the stationary phase?
Where the molecules can't move. It is a solid or a really thick liquid
What is the mobile phase?
Where the molecules can move. This is always a liquid or a gas
What are ions?
An atom or molecule with an overall positive or negative charge due to the loss or gain of an electron
What are cations?
Positively charged ions (lose electrons)
What are anions?
Negatively charged ions (gain electrons)
What is electrostatic attraction?
Attraction between opposite charges
What is an ionic lattice?
A giant structure of ions that held together by ionic bonds that have a regular, repeating arrangement
Why do ionic compounds have high melting and boiling points?
They have strong ionic bonds so it takes large amounts if energy to overcome forces
Why don't ionic compounds conduct electricity when solid?
The ions in solids are not free to move as they are held together by strong forces
In what state do ionic compounds conduct electricity?
Molten or aqueous state
What is covalent bonding?
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
What are simple molecular structures?
When a substance consists of molecules with inter molecular forces of attraction
Why do simple molecular substances have low melting and boiling points?
There are weak intermolecular forces although the covalent bonds or intramolecular forces are not broken
Why does relative molecular mass increase the melting point and boiling point?
There are more inter molecular forces that need to be broken
What is a giant covalent structure?
A huge 3D network of covalently bonded atoms
Why do giant covalent structures have high melting and boiling points?
Large amounts of energy are needed to overcome strong covalent bonds
What is a polar covalent bond?
A covalent bond in which electrons are not shared equally
Why do atoms bond?
Because they want to be stable by gaining a full valence shell
What is a molecule?
A group of atoms bonded together
What is an octet?
8 valence electrons
What is valence?
The outershell
What is electronegativity?
Ability to attract electrons
What is bond length?
The distance between the nuclei of two bonded atoms
What are allotropes?
Different forms of the same element