Chemical Changes And Structure

Question 1

How are elements arranged on the periodic table

Answer 1

By increasing atomic number

Question 2

What do elements in the same group have in common

Answer 2

They have the same number of outer electrons

Question 3

How do elements in the same group differ

Answer 3

Going down a group elements have an extra electron shell

Question 4

What is the trend in elements across a period on the periodic table

Answer 4

Elements add an outer electron across the periodic table, they also change from metal to non metal elements

Question 5

4 types of bonding found in the first 20 elements

Answer 5

Metallic
Covalent molecular
Covalent network
Monatomic

Question 6

Which of the First 20 elements are metallic

Answer 6

Lithium
beryllium
Sodium
Magnesium
Aluminium
Potassium
Calcium

Question 7

Which of the first 20 elements are covalent molecular

Answer 7

H2
N2
O2
F2
CO2
P4
S8
Carbon in the form of fullerene C60

Question 8

Which of the first 20 elements are covalent networks X3

Answer 8

Boron
Silicon
Carbon (diamond, graphite)

Question 9

Which of the first 20 elements are monatomic

Answer 9

Helium
Neon
Argon

Question 10

What is meant by covalent radius

Answer 10

The measure of the size of an atom from the nucleus to outermost electron

Question 11

Describe the trend in a covalent radius going down a group

Answer 11

Covalent radius increases as the number of occupied shells increase

Question 12

Describe trend in covalent radius going along a period

Answer 12

Covalent radius decreases across the period as the nuclear charge increases

Question 13

What is meant by the first ionisation energy

Answer 13

The energy required to remove one mole of electrons from one mole of gaseous atoms

Question 14

What is meant by the second ionisation energy

Answer 14

The energy required to remove the second mole of electrons from one mole of gaseous atoms

Question 15

What is meant by the second ionisation energy

Answer 15

The energy required to remove the second mole of electrons from one mole of gaseous atoms

Question 16

Equation for the first ionisation energy of magnesium

Answer 16

Mg ——> Mg+ + e-

Question 17

Equation for the second ionisation energy for calcium

Answer 17

Ca+ ——> Ca2+ + e-

Question 18

Equation for third ionisation energy of aluminium

Answer 18

Al2+ ——> Al3+ + e-

Question 19

Equation for third ionisation energy of aluminium

Answer 19

Al2+ ——> Al3+ + e-

Question 20

What is meant by electro negativity

Answer 20

A measure of the attraction which an atom has for shared electrons in the bond

Question 21

Describe the trend of electro negativity going down a group

Answer 21

Electro negativity decreases due to increase in shielding effect

Question 22

Describe the trend of electro negativity across a period

Answer 22

Increases due to the increase in nuclear charge

Question 23

How are covalent bonds formed

Answer 23

The result of two positive nuclei being held together by their common attraction for the shared pair of electrons

Question 24

What is meant by polar covalent bonds

Answer 24

Form when atoms in a bind have different electro negativity values

Question 25

What happens to the electrons in a polar covalent bond

Answer 25

The atom with a larger electro negativity value attracts the bonding electrons closer to it, this means that it has a delta negative charge and the other atom has a delta positive charge

Question 26

What is meant by the term pure covalent

Answer 26

Pure covalent bonds are formed when the atoms in the bond have the same electro negativity value

Question 27

Describe the bonding continuum

Answer 27

The bonding continuum shows the bonds by increasing ionic character It goes from pure covalent bonds < polar covalent bind < ionic bond

Question 28

Describe how the states of compounds at room temperature can help identify the type of bonding

Answer 28

- covalent networks are solid - covalent molecular are gas or liquid - ionic substances are solids

Question 29

Describe how the melting points of compounds can help identify the type of bonding

Answer 29

Covalent molecular have low melting points, covalent networks and ionic substances have high melting points

Question 30

Describe the solubility of different compounds

Answer 30

Solubility decreases as molecules increase in size. Polar covalent compounds and ionic compounds tend to be soluble in water and other polar solvents, nonpolar compounds are soluble and nonpolar solvents.

Question 31

Describe the electrical conductivity of different compounds

Answer 31

Covalent molecular and covalent networks do not conduct electricity except graphite. Ionic bonds can conduct when molten or in a solution

Question 32

What is meant by an intermolecular force

Answer 32

Act between molecules these are knows as van der waals forces

Question 33

3 types on inter molecular force

Answer 33

London dispersion force Permanent dipole permanent dipole Hydrogen bonding

Question 34

How do London dispersion forces arise

Answer 34

Formed by the electrostatic attraction between temporary dipoles and induced dipoles which are caused by the movement of electrons

Question 35

Where are London dispersion forces found

Answer 35

Can operate between all atoms and molecules

Question 36

Strength of LDFs

Answer 36

LDF is the weakest intermolecular force LDF gets stronger when there are more electrons as the strength of LDF increase the melting/boiling point increases

Question 37

Explain when a molecule can be described as being polar

Answer 37

When they have permanent dipole - once end of the molecule is positive the other is negative caused by the atoms in the molecule having different electro negativities

Question 38

Explain when a molecule can be described as being non polar

Answer 38

When the shape of the molecule is symmetrical

Question 39

Describe a hydrogen bond

Answer 39

Formed between one molecule which contains hydrogen and another molecule which contained either nitrogen oxygen or fluorine

Question 40

Strength of a hydrogen bond

Answer 40

Strongest intermolecular force

Question 41

Explain how inter molecular forces of attraction affect a molecules physical properties

Answer 41

The higher the inter molecular force the higher the melting and boiling points the string the inter molecular force also increases viscosity

Question 42

Why does ammonia and water have high melting points

Answer 42

They have hydrogen bonds between their molecules which increases the melting point

Question 43

Explain how to fully predict the solubility of a compound

Answer 43

Like dissolves like, so polar compounds will dissolve in polar solvents and non polar compounds will dissolve in non polar solvents

Question 44

What is meant by the term oxidation

Answer 44

The loss of electrons it can also mean the gain of oxygen or loss of hydrogen

Question 45

What is meant by the term reduction

Answer 45

The gain of electrons it can also mean the loss of oxygen or gain of hydrogen

Question 46

What is meant by a redox reaction

Answer 46

When oxidation and a reduction reaction take place at the same time

Question 47

What is meant by the term reducing agent

Answer 47

A substance that donates electrons it is oxidised itself

Question 48

What is meant by an oxidising agent

Answer 48

A substance that accept electrons it is reduced itself

Question 49

Where are oxidising and reducing agents found in the periodic table

Answer 49

Strongest reducing agents are group 1 Strongest oxidising agents group 7

Question 50

How to identify oxidising and reducing agents by their electronegativities

Answer 50

Elements with low electronegativities can form ions by losing electrons so act as reducing agents

Question 51

Name some compounds that act as oxidising agents

Answer 51

Permanganate, dichromate and hydrogen peroxide

Question 52

Uses of oxidising agents

Answer 52

Used to kill fungi bacteria and as a bleach