Definitions Mod 2

Question 1

What is meant by the term isotope

Answer 1

• Atoms of the same element with different numbers of neutrons

Question 2

What is meant by the term relative atomic mass

Answer 2

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

Question 3

What is meant by the term relative isotopic mass

Answer 3

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

Question 4

What is meant by the term empirical formula

Answer 4

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

Question 5

What is meant by the term molecular formula

Answer 5

• The number and type of atoms of each element in a molecule

Question 6

What is meant by the term ionic bonds

Answer 6

• The electrostatic attraction between positive and negative ions

Question 7

What is meant by the term covalent bond

Answer 7

• Shared pair of electrons

Question 8

What is meant by the term dative covalent bond

Answer 8

• Shared pair of electrons which has been provided by only one of the bonding atoms

Question 9

What is meant by the term average bond enthalpy

Answer 9

• The enthalpy change on breaking one mole of bonds of gaseous covalent bond is broken

Question 10

What is meant by the term electronegativity

Answer 10

• The ability of an atom to attract electrons in a covalent bond

Question 11

What is meant by the term acid

Answer 11

• Proton donor (H+)

Question 12

What is meant by the term base

Answer 12

• Proton acceptor (H+) from an acid

Question 13

What is meant by the term alkali

Answer 13

• Type of base that dissolves in water forming OH- ions

Question 14

What is meant by the term salt

Answer 14

• Chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or an ammonium ion, NH4+

Question 15

What is meant by the term standard solution

Answer 15

• A Standard solution is a solution with a precisely known concentration

Question 16

What is meant by the term first ionisation energy

Answer 16

• Is the energy required to remove one electron from each atom in 1 mole of gaseous atoms

Question 17

What is meant by the term orbital

Answer 17

• An orbital is a region around the nucleus that can hold up to two electrons with opposite spins

Question 18

What is meant by the term metallic bonding

Answer 18

• The electrostatic attraction between positive metal ions in the lattice and delocalised electrons

Question 19

Define the term second ionisation energy

Answer 19

• The energy required to remove one electron from each ion with 1+ charge in 1 mole of gaseous ions

Question 20

Electron pair repulsion theory

Answer 20

• Electron pairs repel one another as far as possible
• The shape depends upon the number and type of electron pairs surrounding the central atom
• Lone pairs of electrons are more ‘repelling’ than bonded pairs of electrons

Question 21

Polar molecule

Answer 21

• There is a difference in electronegativites
• The molecule is not symmetrical
• Dipoles do not cancel out

Question 22

Non-polar

Answer 22

• The molecule is symmetrical

* The dipoles due to polar bonds cancel out

Question 23

Induced dipole-dipole interactions/ London forces

Answer 23

• Uneven distribution of electrons
• Creates or causes an instantaneous dipole or temporary dipole
• Causes induced dipoles in neighbouring molecules

Question 24

Ionic lattice

Answer 24

• Repeating pattern of oppositely charged ions