Chemistry CCEA AS Level 1.2 (Atomic Structure)

atomic number

The number of protons in the nucleus of an atom

mass number

The total number of protons and neutrons in the nucleus of an atom

ion

A charged atom, formed by the loss or gain of electrons

RAM

The average mass of one atom of an element relative to 1/12 of the mass of an atom of carbon-12

isotope

Atoms which have the same atomic number but a different mass number

orbital

A region of space within an atom that can hold up to 2 electrons with opposite spins

What does an s orbital look like?

What does a p orbital look like?

How many electrons than a s sub-shell hold?

2

How many electrons can a p sub-shell hold?

6

How many electrons can a d sub-shell hold?

10

1st ionisation energy

The energy required to convert one mole of gaseous atoms in gaseous ions with a single positive charge

What is ionisation energy influenced by?

- Nuclear charge

- Electron shielding

- Atomic radius

- Filled/half-filled shells

nuclear charge

The greater the charge the stronger the attraction for the outer electrons, meaning the ionisation energy is higher

electron shielding

Inner electron shells repel the outer-shell electrons and also shield the outer electrons from the effects of the nuclear charge reducing the net attractive force on the outer electrons. This means the outer electrons are less strongly held and ionisation value is lower

atomic radius

The larger the atomic radius the further the electron is from the nucleus and the less energy is need to remove them as the nuclear attraction experienced by the electron is small

filled/half-filled shells

Extra stability is achieved when subshells are filled or half-filled, meaning the ionisation energy is greater

RIM

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

RFM

the average (weighted mean) mass of a formula unit relative to 1/12 of the mass of an atom of carbon-12

RMM

The average (weighted mean) mass of a molecule relative to one-twelfth of the mass of an atom of carbon-12.

2nd ionisation energy

The energy required to convert one mole of gaseous ions with a single positive charge into gaseous ions with a double positive

charge.

3rd ionisation energy

The energy required to convert one mole of gaseous ions with a double positive charge into gaseous ions with a triple positive

charge.