Chemistry Key Definitions F321

Question 0

MASS NUMBER

Answer 0

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

Question 1

ATOMIC NUMBER

Answer 1

The number of protons in the nucleus of an atom.

Question 2

RELATIVE ISOTOPIC MASS

Answer 2

The mass of an atom of an isotope compared with 1/12 of the mass of an atom of C-12.

Question 3

RELATIVE ATOMIC MASS

Answer 3

The weighed mean mass of an atom of an element compared with 1/12 of the mass of an atom of C-12.

Question 4

ISOTOPES

Answer 4

Atoms of the same element with a different number of neutrons.

Question 5

ATOMIC ORBITAL

Answer 5

A region within an atom that can hold up to two electrons with opposite spin.

Question 6

s/p/d BLOCK ELEMENT

Answer 6

Highest energy sub-shell is a s/p/d sub-shell.

Question 9

ACID

Answer 9

Release H+ ions in solution (proton donor).

Question 10

MOLE

Answer 10

The amount of substance containing as many particles as there are carbon atoms in exactly 12g of C-12.

Question 11

AVOGADRO’S CONSTANT

Answer 11

The number of particles per mole of a substance (6.02x10^23).

Question 12

MOLAR MASS

Answer 12

The mass, in g, per mole of a substance. Units are gmol-1.

Question 13

EMPIRICAL FORMULA

Answer 13

The simplest whole number ratio of atoms of each element present in a compound.

Question 14

MOLECULAR FORMULA

Answer 14

The actual number of atoms of each element in a molecule.

Question 15

WATER OF CRYSTALLISATION

Answer 15

The water present in a compound giving the compound a crystalline appearance.

Question 16

ANHYDROUS

Answer 16

When all the waters of crystallisation have been removed from a compound.

Question 17

HYDRATED

Answer 17

When water of crystallisation is present in a crystal compound.

Question 18

FIRST IONISATION ENERGY

Answer 18

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions. Units are KJmol-1.

Question 19

SUCCESSIVE IONISATION ENERGY

Answer 19

A measure of the energy required to remove each electron in turn.

Question 20

METALLIC BONDING

Answer 20

The attraction of positive metal ions to delocalised electrons.

Question 21

ALKALI

Answer 21

A soluble base that releases OH- ions when in solution.

Question 22

COVALENT BOND

Answer 22

The sharing of a pair of electrons between two atoms.

Question 23

BASE

Answer 23

A proton acceptor.

Question 24

PERIODICITY

Answer 24

The repeating pattern of trends across different periods.

Question 25

IONIC BOND

Answer 25

The electrostatic attraction between oppositely charged ions.

Question 26

SALT

Answer 26

A compound produced when an H+ ion from an acid is replaced by a metal or another positive ion, such as the ammonium ion.

Question 27

DATIVE COVALENT BOND

Answer 27

The sharing of a pair of electrons between two atoms, where only one of the atoms supplies both the electrons shared.

Question 28

ELECTRONEGATIVITY

Answer 28

The ability of an atom to attract the bonding electrons towards itself in a covalent bond.

Question 29

OXIDATION NUMBER

Answer 29

A measure of the number of electrons that an atom uses to bond with atoms of a different element.

Question 30

OXIDATION

Answer 30

The loss of electrons/an increase in oxidation number (state).

Question 31

OXIDISING AGENT

Answer 31

A reagent which oxidises another species (gets reduced itself).

Question 32

REDUCTION

Answer 32

The gain of electrons/a decrease in oxidation number (state).

Question 33

REDUCING AGENT

Answer 33

A reagent which reduces another species (gets oxidised itself).

Question 34

REDOX

Answer 34

A reaction where both oxidation and reduction take place.

Question 35

DISPLACEMENT REACTION

Answer 35

A reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its halide ions.

Question 36

DISPROPORTIONATION

Answer 36

A reaction in which an element is simultaneously oxidised and reduced

Question 37

HYDROGEN BOND

Answer 37

A dipole-dipole attraction between a slightly positive hydrogen on one molecule and a lone pair of electrons on a highly electronegative atom (N, O, F) of another molecule.