2A - Atoms & Redox definitions

Question 1

Isotope

Answer 1

Atoms of the same element with different number of neutrons and different masses

Question 2

Atomic number

Answer 2

The number of protons in the nucleus of an atom

Question 3

Mass number

Answer 3

The number of particles (protons and neutrons) in the nucleus

Question 4

Ion

Answer 4

A positively or negatively charged atom (or covalently bonded) group of atoms (a molecular ion)

Question 5

Relative isotopic mass

Answer 5

The mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon-12

Question 6

Relative atomic mass

Answer 6

(Ar)

The weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12

Question 7

Relative molecular mass

Answer 7

The weighted mean mass of a molecule compared with 1/12th of the mass of an atom of carbon-12

Question 8

Relative formula mass

Answer 8

The weighted mean mass of a formula unit compared with 1/12th of the mass of an atom of carbon-12

Question 9

1st Ionisation energy

Answer 9

The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms from 1 mole of gaseous 1+ ions

Question 10

Electron transfer: Oxidation and reduction

Answer 10

Oxidation = loss of electrons

Reduction = gain of electrons

Question 11

Oxidation numbers to explain redox: Oxidation / reduction

Answer 11

Oxidation = Increase in an oxidation number (more +VE)

Reduction = Decrease in an oxidation number (less +VE)

Question 12

Iso-electronic

Example?

Answer 12

Ions that have the same number of electrons

E.G.

Al³⁺ and F^- both have 10 electrons

Question 13

Electron shielding

Answer 13

The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons