Chemistry Unit 1

Question 1

Describe how elements are arranged on the periodic table

Answer 1

Elements on the periodic table are arranged by increasing atomic number.

Question 2

Describe the trends on the periodic table

Answer 2

The position of elements on the Periodic Table allows us to make predictions of their physical properties and chemical behaviour.

Question 3

Describe the trends on the periodic table along a period

Answer 3

Going along a period, elements move from metallic to non-metallic and add an outer electron each time.

Question 4

Describe the trends on the periodic table down a group

Answer 4

Going down a group in the periodic table, the elements contain the same number of outer electrons but an extra outer shell each time.

Question 5

What is a metallic lattice?

Answer 5

Li, Be, Na, Mg, Al, K, Ca

Question 6

What is a covalent molecular?

Answer 6

H2, N2, O2, F2, Cl2, P4, S8 and fullerenes (eg C60)

Question 7

What is a covalent network?

Answer 7

B, C (diamond and graphite), Si

Question 8

What is a monatomic?

Answer 8

Noble gases

Question 9

What is the covalent radius?

Answer 9

The covalent radius is a measure of the size of an atom.

Question 10

What does the covalent radius do across and down the periodic table?

Answer 10

Across a period, the covalent radius decreases as the nuclear charge increases. Going down a group, the covalent radius increases as the number of occupied shells increases.

Question 11

State the definition of the term first ionisation energy

Answer 11

First ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms.

Question 12

State the definition of the term second ionisation energy

Answer 12

Second ionisation energy is the energy required to remove the 2nd mole of electrons.

Question 13

Explain the trends in ionisation energy on the periodic table

Answer 13

Across a period, the ionisation energy tends to increase as the nuclear charge increases. Down a group, the ionisation energy decreases due to increased screening effect.

Question 14

State the definition of the term electronegativity

Answer 14

Electronegativity is a measure of the attraction which an atom has for the electrons in a bond.

Question 15

Explain the trends in electronegativity on the periodic table going down

Answer 15

Going down a group, the electronegativity decreases due to the screening effect of the inner shell electrons.

Question 16

Explain the trends in electronegativity on the periodic table going across

Answer 16

Across a period, the electronegativity values increase due to the increasing nuclear charge.

Question 17

State how covalent bonds are formed

Answer 17

A covalent bond occurs between non-metal elements due to the attraction for the shared pair of electrons.

Question 18

How are polar covalent bonds formed?

Answer 18

Polar covalent bonds are formed when the attractions of the atoms for the pair of bonding electrons are different.

Question 19

What happens when polar covalent bonds are formed?

Answer 19

One atom will become delta positive (δ+) and the other delta negative (δ-). The atom with the higher electronegativity will be delta negative (δ-).

Question 20

What is the spatial arrangement in polar covalent molecules?

Answer 20

Not all substances with polar covalent bonds will be polar molecules due to the spatial arrangement of the atoms.

Question 21

What does ionic formula show?

Answer 21

Ionic formula shows the simplest ratio of each type of ion and can show the charge of each ion.

Question 22

Describe the bonding continuum

Answer 22

The bonding continuum shows the ‘continuum’ of states from covalent to ionic bonds.

Question 23

Type of bonding in room temperature

Answer 23

Covalent networks - solid; Covalent molecular - gas or liquids; Ionic substances - solid.

Question 24

Type of bonding in melting points

Answer 24

Covalent molecular - low melting points; Covalent network - high melting points; Ionic bonds - high melting points.

Question 25

What is solubility meaning?

Answer 25

Solubility decreases as molecules increase in size. Polar covalent compounds and ionic substances tend to be soluble in water.

Question 26

what bonds conduct?

Answer 26

Covalent bonds do not conduct, with the exception of carbon in the form of graphite ionic bonds can conduct when molten or in solution.

Question 27

State the 3 types of intermolecular (van der Waals) forces

Answer 27

London dispersion forces (LDFs), Permanent dipole-permanent dipole (Pd-Pd) forces, Hydrogen bonding.

Question 28

How are LDFs formed?

Answer 28

LDFs are formed by the electrostatic attraction between temporary dipoles and induced dipoles.

Question 29

Why are LDFs always present?

Answer 29

Electrons are continuously moving, leading to LDFs between all atoms and molecules.

Question 30

LDF characteristics

Answer 30

LDFs are the weakest intermolecular force and get stronger with more electrons.

Question 31

Explain when a molecule is described as polar

Answer 31

Molecules are polar when they have a permanent dipole.

Question 32

Describe a permanent dipole-permanent dipole interaction

Answer 32

Dipole-Dipole interaction is the attraction between oppositely charged ends of polar molecules.

Question 33

Pd-Pd interactions characteristics

Answer 33

Pd-Pd interactions are stronger than LDFs and are in addition to LDFs.

Question 34

Describe a hydrogen bond

Answer 34

Hydrogen bonds are Pd-Pd interactions found between molecules which contain highly polar bonds.

Question 35

Where can hydrogen bonds form between?

Answer 35

Hydrogen - Nitrogen; Hydrogen - Oxygen; Hydrogen - Fluorine.

Question 36

Hydrogen bonds characteristics

Answer 36

Hydrogen bonds are the strongest intermolecular force, leading to higher melting and boiling points.

Question 37

Explain how intermolecular forces of attraction affect a molecule's physical properties

Answer 37

The stronger the intermolecular force of attraction, the higher the melting and boiling point.

Question 38

Explain why ammonia and water have high boiling points

Answer 38

Ammonia and water have high boiling points due to hydrogen bonding.

Question 39

Explain how to predict the solubility of a compound

Answer 39

Consider whether there is hydrogen bonding and the spatial arrangement of polar covalent bonds.

Question 40

What is reduction?

Answer 40

Reduction is the gain of electrons by a reactant.

Question 41

What is oxidation?

Answer 41

Oxidation is the loss of electrons by a reactant.

Question 42

State the definition of a redox reaction

Answer 42

A Redox Reaction is when an oxidation and a reduction reaction takes place at the same time.

Question 43

What is an oxidising agent?

Answer 43

Oxidising agent is a substance that accepts electrons.

Question 44

What is a reducing agent?

Answer 44

Reducing agent is a substance that donates electrons.

Question 45

What can elements with low electronegativities do?

Answer 45

Elements with low electronegativities can form ions by losing electrons.

Question 46

Where are oxidising agents on the electrochemical series

Answer 46

Oxidising agents are at the bottom left side of the electrochemical series.

Question 47

Where are reducing agents on the electrochemical series?

Answer 47

Reducing agents are at the top right column of the electrochemical series.

Question 48

What can oxidising agents be used for?

Answer 48

Oxidising agents can be used to kill fungi and bacteria and as a bleach.

Question 49

Balance ion equations stages

Answer 49

1. Balance the ions; 2. Balance the oxygen by adding water; 3. Balance the hydrogen by adding hydrogen ions; 4. Balance the change.

Question 50

Combine ion-electron equations to produce redox equations stage 1

Answer 50

Before combining the equations, the number of electrons must be equal in each equation.

Question 51

Combine ion-electron equations to produce redox equations stage 2

Answer 51

Combine equations.

Question 52

Combine ion-electron equations to produce redox equations stage 3

Answer 52

Cancel out electrons and anything else that appears on both sides.

Question 53

how to find the least ionic character

Answer 53

least ionic means the smallest electronegativity difference

Question 54

how to find if an Atom is larger than an ion

Answer 54

compare the number of occupied electron shells

Question 55

what elements don't contain LDFs

Answer 55

covalent network

Question 56

what elements tend to be reduced

Answer 56

elements with high electronegativities tend to be reduced

Question 57

which atom has the greatest attraction for bonding electrons

Answer 57

the atom which is the most electronegative

Question 58

how to calculate enthalpy change

Answer 58

you change the delta h based on if its on the right side (leave it how it is), wrong side (change sign), wrong number (multiply or divide)

Question 59

secondary

Answer 59

attached to 2 carbons

Question 60

primary

Answer 60

at the end of the carbon chain

Question 61

tertiary

Answer 61

attached to a carbon with no hydrogen atoms attached

Question 62

glycerol

Answer 62

propane-1,2,3-triol

Question 63

what has to be present for initiation

Answer 63

UV