Module 2 Foundations In Chemistry

Question 1

Bohr model

Answer 1

Describes an atom as a small dense nucleus with electrons orbiting around the nucleus.

Question 2

Relative abundance

Answer 2

The amount of one substance compared to another

Question 3

Relative atomic mass

Answer 3

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

Question 4

Relative isotopic mass

Answer 4

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

Question 5

Relative formula mass

Answer 5

The mass of the formula unit of a compound with a giant structure.

Question 6

Relative molecular mass

Answer 6

The mass of a simple molecule

Question 7

Ionic compound

Answer 7

A compound with is made up of oppositely charged ions that are held together by strong electrostatic forces.

Question 8

Amount of substance

Answer 8

The quantity that has moles as its units can be calculated with (n=m/mr) , (n=pv/rt) , (n=cv)

Question 9

Atom economy

Answer 9

A measure of the amount of starting material that end up as useful products. %atom economy=(molecular mass of desired product/sum of mass of all reactants) x100

Question 10

Avagadros constant

Answer 10

6.022x10*23

Question 11

Empirical formula

Answer 11

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

Question 12

Percentage yield

Answer 12

The percentage ratio of the actual yield of product from a reaction compared with the theoretical yield

Percentage yield=(actual yield/theoretical yield)x100

Question 13

Relative molecular mass

Answer 13

The average mass of one molecule of an element or compound compared to 1/12th the mass of an atom of carbon 12

Question 14

Acid

Answer 14

Compounds that release H+ ions im aqueous solution

Question 15

Alkali

Answer 15

Water soluble bases that release OH- ions in aqueous solution

Question 16

Base

Answer 16

A substance that can accept H+ ions from another substance

Question 17

Neutralisation

Answer 17

A reaction between H+ and OH- forming water. This may be a reaction between a acid and a base to form a salt

Question 18

Strong acid

Answer 18

An acid that completely dissociates in solution

Question 19

Titration

Answer 19

A technique used to determine the amount of one solution of a known concentration required to completely react with a known volume of another solution of unknown concentration

Question 20

Weak acid

Answer 20

An acid that only partly dissociates in solution

Question 21

Oxidation

Answer 21

Loss of electrons

Question 22

Oxidation number

Answer 22

A number that represents the number of electrons lost or gained by an atom of an element. A positive oxidation number indicates the loss of electrons.

Question 23

Redox

Answer 23

A reaction where on element is oxidised and another is reduces

Question 24

Orbital

Answer 24

A region of space around the nucleus that can hold up to 2 electrons with opposite spins.

Question 25

She’ll

Answer 25

The orbit that an orbital is in around the nucleus of an atom. The outermost shell is the valence shell.

Question 26

Sub shell

Answer 26

A subdivision of the electronic shells into different orbitals. The types of subshell are s p d f

Question 27

Average bond enthalpy

Answer 27

The average heat energy required to break a bond

Question 28

Covalent bond

Answer 28

A strong bond formed between 2 atoms due to the electrostatic attraction between a shared pair of electrons.

Question 29

Dative covalent

Answer 29

A type of covalent bond where both of the electrons in the shared pair come from one atom (common example NH4+.

Question 30

Electronegativity

Answer 30

The ability of an atom to attract bonding electrons in a covalent bond. Quantified using Pauling’s electronegativity values.

Question 31

EPRT (Electron pair repulsion theory)

Answer 31

Pair of electrons around a nucleus repel each other so the shape that the molecule adopts as three pairs of electrons positioned as far apart as possible. Lone pairs offer more rupulsion than bonding pairs as they are closer to the nucleus of the central atom.

Question 32

Hydrogen bonding

Answer 32

A type of intermolecular bonding that occurs between molecules containing N, O, F and a H atom.

Question 33

Intermolecular forces

Answer 33

Interactions between different molecules. Types of intermolecular forces including permanent dipole-dipole interactions induces dipole interactions as well as hydrogen bonding

Question 34

Ionic bond

Answer 34

The electrostatic forces of attraction between positive and negative ions

Question 35

London forces

Answer 35

Induced dipole-dipole interactions cause when the random movement of electrons creates a temporary dipole in one molecule which then induces a dipole in a neighbouring molecule.

Question 36

Lone pair

Answer 36

A pair of valence electrons not involved in bonding

Question 37

Macroscopic properties

Answer 37

Properties of a bulk material rather than individual atoms.

Question 38

Linear

Answer 38

The shape of a molecule im which the central atom has 2 bonding pairs (180 bond angle)

Question 39

Non linear

Answer 39

The shape of a molecular in which the central atom has 2 bonding pairs and 2 lone pairs

Question 40

Octahedral

Answer 40

The shape of a molecule in which the central atom has 6 bonding pairs (90 bond angle)

Question 42

Permanent dipole

Answer 42

A permanent uneven distribution of charge

Question 43

Pyramidal

Answer 43

The shape of a molecule in which the central atom has 3 bonding pairs and 1 lone pair(107) bond angle)

Question 44

Tetrahedral

Answer 44

The shape of a molecule in which the central atom has 4 bonding pairs(109.5)

Question 45

Trigonal bipyramidal

Answer 45

The shape of a molecule that has 5 bonding pair(90 and 120 bond angles)

Question 46

Trigonal planar

Answer 46

The shape of a molecule that has 3 bonding pairs