chemistry

UNIT 3

UNI 4

UNIT 1

Solids

Liquids

gases

tight compact arrangement

loose arrangments

losse but still touching arrangments

Relative atomic mass

Isotopes

Different form of elements with the same number of protons but different number of neutrons

Sum of (isotope abundance + isotope mass) ÷ 100

highest energy

medium energy

lowest energy

Changes of state

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Atoms

Elements

Compounds

The smallest particle of an element

2 or more substances chemically combined

Element made of one type of atom

Mixtures

not chemically joined substances but can be seperated

seperation techniques

Solubility

How much a substance will dissolve in a given volume of a solvent

surface area of solute

increase rate of stirring

Diffusion

The net movement of particles from an area of low concentration to high concentration

increase conc. gradient

larger surface area

Exothermic

Endothermic

heat exiting

heat entering

Increase temperature

Solvent

Solute

solution

saturated solution

substance that boils over a range of temps will be a mixture not a pure compound

factional distillation

components of a chemical mixture is separated in fractions by their different boiling/ melting points

crystalisation

the solidification of a liquid substance (must add heat)

simple distillation

purifying a liquid compound by heating into vapour then condensed back into a liquid

temperature of solvent

rf values

distance travelled by pigment ÷ distance travelled by solvent

chemical substance that dissolves a solute = solution

substance being dissolved

homogeneous solution of 2 or more substances (can exist in any phase)

maximum amount of solute that dissolves in a solvent (crystals may form)

vibrate against each other

slide around each other

move and collide with each other

UNIT 2

atomic structure

protons

neutrons

electrons

-1 charge

+1 charge

0 charge

1/2000

1 (mass)

1 (mass)

Alkali metals

lithium

sodium

Potassium

  • floats on surface + bubbles

melts into sphere + moves on surface quickly + bubbles

lilac flame + floated rapidly

They all turn universal indicator blue

reactivity

reactivity increases as you go down group 1 because the electrons are arranged so there is one extra electron on the outermost shell. This makes it reactive. as the distance from the nucleus to the single electron increases, the reactivity does as well

positive always attract negatives

the attraction between the positively charged nucleus ad the outermost electrons get weaker as the atom size increases. it makes it easier to lose the outer electron

noble gases

not reactive because already have complete outer shell

isotopes

atoms of the same element but with different number of neutrons but same number of protons

electrons determine the chemical behaviour

relative atomic mass

average mass of all the different isotopes

ionic bonding

electrostatic attraction between oppositely charged ions in a chemical compound.

covalent bonding

formed between atoms when pairs of electrons are shared

molecular ions

Screenshot 2024-04-28 at 12.28.28 PM

electrostatic force of attraction between positively charged ions. (very strong and need stronger input of energy to overcome

ionic compounds have high melting points

electrostatic attraction between a shared pair of electrons and the nuclei on two atoms (very strong)

covalent molecules have low melting and boiling points

weak electrostatic forces between molecules (weak amount of energy to overcome)

non metal + non metal

non metal + metal

rates of reactions

for particles to react, they must have sufficient amount of activation energy to react with each other

catalyst

temperature

surface area

as the temperature increases, the rate of reaction also increases since the particles have more kinetic energy making them move around faster which results in more successful collisons per unit time.

pressure

a catalyst is a substance that is added to a chemical to speed up the reaction. catalyst will lower the activation energy and allow a new pathway for the particles to bond. this will increase the rate of reaction and form more successful collisions per unit time

the rate of reaction will increase with a larger surface area because more particles are exposed to the reactant meaning there will be more successful collisions per unit time.

concentration

at a higher concentration, the rate of reaction will be quicker because there will be more reactant particles in a set volume.

As the pressure increases so does the rate of reaction. Increased pressure is when particles are pushed together in an area so there will be smaller amount of space to move around. this means there will be more chance of successful collisions per unit time

rate of reaction = change in reactant / time

activation energy is the minimum amount of energy for the reaction to start happening and to provide energy for the particles to start moving

ion

atom or a group of atoms with one or more positively or negatively charged electron

molecules

a group of atoms bonded together

unit 6