Chemistry - Unit 1 (0620)

Solid to liquid

Melting

Liquid to solid

Freezing

Liquid to gas

Evaporating or boiling

Gas to liquid

Condensing

Solid to gas

Subliming

Solids

1) held together by strong forces keeps them close together to form a very regular lattice arrangement.
2)the particles don't move from their positions, so all solids keep a definite shape and volume, but don't flow like liquids.
3)particles vibrate around fixed positions- the hotter the solid becomes, the more they vibrate.

Liquids

1) forces holding the particles together are weaker than solids so they'e randomly arranged and free to move, but tend to stick closely together.
2)they have a definite volume but don't keep a definite shape, and will flow to fill the bottom of a container.
3)particles are constantly moving and sliding past each other

Gases

1) force of attraction between particles is very weak- they're free to move and far apart. particles travel in straight lines (before they bump into another particle).
2)they don't keep a definite shape or volume and will always fill any container.
3)particles move constantly with random motion. the hotter the gas gets, the faster they move.

3 states of matter

Solid, liquid, gas - all matter exists as one of these

Kinetic particle theory

How the particles in matter move and are arranged in each of the states of matter

Solid - particle distance

Particles packed very closely

Solid - energy level of particles

Each particle in a a solid has a small amount of energy. Less than a liquid and gas

Solid - particle movement

Vibrate (move to and fro) around its fixed position

Liquid - particle distance

Closely packed together

liquid - energy level of particles

More energy than a solid but less than a gas

Liquid - particle movement

Particles have enough energy to move around randomly and slide past each other and in any direction within the liquid

sublimation

when a material is heated and changes straight from a solid to a gas (skipping liquid stage). Sublimation happens only to a small number of substances at room temperature and pressure

Gas - particle distance

Particles are far apart

gas - particle energy level

Particles have sufficient energy to move around quickly in any direction

Gas - particle movement

Particles move around quickly and in any direction within their container

A change of state occurs when...

A change of state occurs if a material changes from one state to another because energy is either given to it or taken away from it

Melting point of ice/water

0 C.
Ice melts into water
Water freezes/solidifies into ice

Boiling point of water

100 C
water boils into steam
steam condenses into water

Kinetic energy

The energy that a particle possesses due to its motion

Solid to gas

Subliming

Evaporating

The transition of the surface molecules of a liquid into a gas below the boiling point. Slower than boiling and happens over a range of temperatures

Physical change

A change in a substance that does not involve a change in the identity of the substance

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Diffusion is fastest in a...

Gas

Speed of Air particles at room temperature

Between 300-400 m/s

Motion of particles in a gas or liquid

Brownian motion

Factors which affect the rate of diffusion

Difference in concentrations (concentration gradient)
Temperature
Mass of particle

Gas Pressure

The force exerted by a gas per unit surface area of an object

What factors affect gas pressure

Temperature, volume, number of particles

Particle

Small portion of matter

Mixture

A combination of two or more substances that are not chemically combined

Compound

A substance made up of atoms of two or more different elements joined by chemical bonds

Non-metal

an element that is not a metal

they conduct heat and electricity poorly. Found on the top right of the periodic table.

Element

A pure substance made of only one kind of atom

Metal

A class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity. Found on left and middle of the periodic table.

Periodic Table of Elements

A chart where all the elements are organized into periods and groups according to their properties

Atom

Smallest particle of an element

Electron

Negatively charged sub atomic particle (1-)

Neutron

A small sub atomic particle in the nucleus of the atom, with no electrical charge

Proton

Positively charged sub atomic particle (1+)

Nucleus

The center of an atom, containing the protons and neutrons

Atomic number

The number of protons in the nucleus of an atom (which also equals the number of electrons)

Atomic mass

the weighted average of the masses of the isotopes of an element relative to carbon-12 isotope

Atomic mass unit (amu)

A unit of mass that describes the mass of an atom or molecule

Electron shell

An energy level representing the distance of an electron from the nucleus of an atom.

Group

A vertical column on the periodic table

Period

A horizontal row on the periodic table

Valency

Equal to the number of electrons that each atom needs to gain, lose or share to fill its outer shell

Nucleon number

Number of protons and neutrons in the nucleus

Inert

Chemically unreactive

Reactivity

the property that describes how readily a substance combines chemically with other substances

Electron configuration

the arrangement of electrons in the orbitals of an atom.

Cooling curve

a diagram that illustrates temperature changes and changes of state for a substance as heat is removed

Heating curve

a diagram that shows the temperature changes and changes of state of a substance as it is heated

Latent heat

Heat absorbed or radiated during a change of state (due to forces of attraction forming or breaking) at a constant temperature and pressure

Forces of attraction forming

Exothermic

Forces of attraction breaking

Endothermic

Pure substances

Only has one type of particle and has a sharp melting and boiling point

Isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

Maximum number of electrons on first shell

2 electrons

Maximum number of electrons on an electron shell (excluding the first)

8 electrons

Neutral atoms contain equal numbers of

Protons and electrons