IB Chemistry SL: Periodic table and bonding

Question 1

Relative atomic mass (Ar)

Answer 1

The relative atomic mass of an element is the weighted average of the masses of the isotopes relative to 1/12 of the mass of a carbon-­‐12 atom.

Question 2

Relative molecular mass (Mr)

Answer 2

The relative molecular mass of a substance is the mass of one molecule of that substance relative to 1/12 of the mass of carbon – 12 atom.

Question 3

Mass Number

Answer 3

The sum of the protons and neutrons in the nucleus of the atom or ion.

Question 4

Atomic Number

Answer 4

is equal to the number of protons in the nucleus of an atom.

Question 5

Isotope

Answer 5

are atoms of the same element with different numbers of neutrons.

Question 6

1st Ionisation Energy

Answer 6

The minimum energy required to remove one mole of electrons from an atom in its gaseous state.

Question 7

Electronegativity

Answer 7

Electronegativity is a measure of the tendency of an atom in a molecule to attract a bonding pair of electrons towards itself.

Question 8

Exothermic Reaction

Answer 8

An exothermic reaction is one that releases heat to the surroundings. (As a result of forming products with stronger bonds than the reactants. Exothermic reactions have negative ∆H values.)

Question 9

Endothermic Reaction

Answer 9

An endothermic reaction is one that absorbs heat from its

surroundings. (As a result of forming products with weaker bonds than the reactants. Endothermic reactions have positive ∆H values.)

Question 10

Electron Affinity

Answer 10

the energy change when 1 mole of gaseous atom gains 1 mole of electron to form a gaseous ion, under standard conditions (technically, this should be called the 1st electron affinity)