2.1.1 2.1.2 2.2.2 3.1.1

isotopes

an atom of an element has the same number of protons but different numbers of neutrons

mass number

A

number of neutrons and protons

atomic number

z

protons

chemical reactions and isotopes

as they have the same number of electrons they react the same waytomic/a

atomic structure of ions

a charged atom

relative isotopic mass

the mass of an isotope relative to 1/12th of the mass of an atom of carbon-12

relative atomic mass

the mass of the weighted mean mass of an atom relative to 1/12th mass of carbon-12

Mass spectrometry

• vaporised and ionised +1 or +2

• ions accelerated, heavier slower so more difficult to deflect

• this separates ions of isotopes

• detected on mass spectrum m/z

• the greater the abundance the larger the signal

• percent on left, m/z on x

Binary compound

contains 2 elements only -ideolyap

polyatomic ions

ion that contains more than one element bonded together e.g. OH-

Shells

energy levels

energy increases as shell num

the shell number is called the principle quantum number m

s orbital

each shell has 1 s orbital

2e-

spherep

p subshell

three p orbitals

2e- each

dumbell

d orbital

five orbitals

f orbital

seven orbitals

sub shells fill

in order of energy levels

electrons in a pair

repel and have opposite spin

s/p/d block

where the highest energy electrons are in these shells

Ionic bonding

The electrostatic attraction between positive and negative ions

Ionic compounds structure

giant ionic lattice

each ion attracts oppositely charged ions in all directions

ionic mp/bp

insufficient energy to overcome the strong electrostatic forces of attraction

greater the ionic charge the stronger the lattice, as stronger attraction between ions

Also can be changed by the size of the ions

ionic solubility

most dissolve in polar solvents, as they break down the lattice and surround ions

in compounds with larger charges even water cannot break

Ions electrical conductivity

• solid ions in fixed position and no mobile charge carriers

• solid ionic lattice breaks down, ions are free to move as mobile charge carriers

covalent bonding

the electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

a covalent bond is the overlap of orbitals

when atoms gain more than 8 e-

they expand their octet

dative covalent bond

a bond where the shared pair of e- has been supplied by only one of the bonding atoms

average bond enthalpy

a measurement of covalent bond strength

electronegativity

across a period nuclear charge increases and atomic radius decreases