Foundations in Chemistry

Question 1

Element

Answer 1

a group of atoms which all have the same number of protons

Question 2

Isotope*

Answer 2

atoms which have the same number of protons but a different number of neutrons

Question 3

Ion

Answer 3

an atom which has different numbers of protons and electrons causing it be be either positively or negatively charged

Question 4

Orbital*

Answer 4

a region around the nucleus of an atom that can hold up to two electrons with opposite spins

Question 5

Relative Atomic Mass*

Answer 5

the weighted mean mass of an atom of an element relative to one twelfth of the mass of an atom of carbon-12

Question 6

Relative Isotopic Mass*

Answer 6

the mass of an atom of an isotope relative to one twelfth of the mass of an atom of carbon-12

Question 7

Relative Molecular Mass

Answer 7

the mass of a molecule relative to one twelfth of the mass of an atom of carbon-12

Question 8

Relative Formula Mass

Answer 8

the mass of a formula unit (of a giant structure) relative to one twelfth of the mass of an atom of carbon-12

Question 9

Molecular Formula

Answer 9

the actual number of atoms of each element in the molecule

Question 10

Empirical Formula*

Answer 10

the simplest whole number ratio of atoms of each element in the compound

Question 11

Hydrated

Answer 11

a crystalline compound containing water molecules

Question 12

Anhydrous

Answer 12

a compound which contains no water molecules

Question 13

Water of Crystallisation

Answer 13

the water molecules that are combined into the crystalline structure of a hydrated compound

Question 14

Acid*

Answer 14

a proton donor/produces H+ ions in aqueous solution

Question 15

Base*

Answer 15

a proton acceptor

Question 16

Alkali*

Answer 16

a soluble base/produces OH- ions in aqueous solution

Question 17

Salt*

Answer 17

a compound where the proton in an acid has been replaced by a metal or ammonium ion

Question 18

Strong Acids*

Answer 18

an acid that completely dissociates in water e.g. HCl, H2SO4, HNO3

Question 19

Weak Acids*

Answer 19

an acid that partially dissociates in water e.g. carboxylic acids

Question 20

Oxidising Agent, [O]

Answer 20

a compound which oxidises another compound by gaining electrons and is reduced

Question 21

Reducing Agent, [H]

Answer 21

a compound which reduces another compound by losing electrons and is oxidised

Question 22

Ionic Bonding*

Answer 22

the strong electrostatic attraction between oppositely charged ions

Question 23

Metallic Bonding*

Answer 23

the strong electrostatic attraction between positive metal ions and the sea of delocalised electrons

Question 24

Covalent Bond*

Answer 24

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

Question 25

Dative Covalent Bond*

Answer 25

a covalent bond where both electrons are donated by one of the atoms

Question 26

Hydrogen Bond*

Answer 26

a strong dipole-dipole attraction between an electron deficient hydrogen atom of -NH, -OH or -HF and a lone pair of electrons on a highly electronegative atom containing O, N, or F in a neighbouring molecule

Question 27

Electronegativity*

Answer 27

the ability of an atom to attract the electrons in a covalent bond

Question 28

Dipole/Polar Bond/Polar Molecule

Answer 28

a covalent bond or molecule where the electron density is shifted more towards one end than the other

Question 29

Permanent Dipole*

Answer 29

a small charge difference across a bond that results from a difference in the electronegativities of the bonded atoms