Chapter Three

Question 1

How do electrons orbit the nucleus

Answer 1

In fixed circular orbits which correspond to specific energy shells/levels of the atom

Question 2

What do electron orbits of a larger radii mean

Answer 2

They correspond to a higher energy level

Question 3

Can electrons occupy the space between energy levels

Answer 3

No, they can only occupy the fixed orbits

Question 4

How can electrons move between energy levels

Answer 4

They absorb or emit energy in the form of electromagnetic radiation or light

Question 5

What does ‘n’ stand for

Answer 5

The electron shells of an atom

Question 6

As the value of n increases the energy levels

Answer 6

Get closer together

Question 7

What did the Niels Bohr model of the atom propose

Answer 7

• Electrons revolve around the nucleus in circular orbits
• The electron orbits correspond to certain energy levels or shells in the atom
• Electrons can only occupy these fixed energy eves and cannot exist between two energy levels
• Electron orbits of a larger radii correspond to a higher energy level

Question 8

Which electrons are involved in chemical reactions

Answer 8

The valence electrons (outer most electrons)

Question 9

What can you predict if you know the number of valence electrons in an atom

Answer 9

The chemical properties of an element

Question 10

How are the elements in a periodic table arranged

Answer 10

• In order of increasing atomic number (rows)
• The number of electrons in the outer shell of an element (columns)

Question 11

Groups

Answer 11

• Going down in vertical columns
• Number of valence electrons in the atom of an element
• Labelled 1-18

Question 12

Periods

Answer 12

• Across the table in rows
• Arrangement of electrons in each atom = to the number of occupied electron shells in the atom
• Labelled 1-7

Question 13

Helium

Answer 13

• In group 18 but only has 2 valence electrons
• it is placed here however as it is unreactive

Question 14

What do the elements in the same group have in common

Answer 14

Chemical properties

Question 15

Alkali metals properties

Answer 15

• Highly reactive with water and oxygen
• Relatively soft metals

Question 16

Halogens properties

Answer 16

• Coloured
• Highly reactive

Question 17

Noble gases properties

Answer 17

• Stable
• Inert/ low reactivity

Question 18

Electron configuration

Answer 18

The number of electrons in each shell, separated by commas starting at the shell with the lowest energy

Question 19

Ion

Answer 19

-A positively or negatively charged atom
- When protons and electrons don’t equal the same amount

Question 20

How do ions form

Answer 20

• Through chemical reactions or addition of energy the total number of electrons in an atom increases or decreases, this changes the electron configuration
• The electrons are gained or lost from the valence shell as they are the most weakly held electrons

Question 21

Negatively charge ions

Answer 21

Anions

Question 22

Positively charged ions

Answer 22

Cations

Question 23

Trends in the periodic table

Answer 23

Summarises the relative properties of elements and explains the trends observed in those properties

Question 24

List the trends in the periodic table

Answer 24

• Electronegativity
• Electrostatic attraction
• Core charge
• Atomic radius
• Ionisation energy
• Metallic character

Question 25

Electrostatic attraction

Answer 25

Holds individual atoms together, holds atoms together in molecules and molecules together in all forms of matter

Question 26

Coulomb's Law

Answer 26

F = k x q1q2/r^2 - q1 and q2 = the magnitudes of the charges involved - r = the distance between them - k = a constant - F = force of attraction

Question 27

Electrostatic attraction strength

Answer 27

- If the size of the charge increases so does the electrostatic attraction - As the distance between the charges increase, the attraction decreases - The strength of the electrostatic attraction is directly proportional to the magnitude of the charges involved

Question 28

Core charge (effective nuclear charge)

Answer 28

A measure of the attractive force felt by the valence electrons towards the nucleus

Question 29

Core charge equation

Answer 29

Number of protons - the number of total inner shell electrons

Question 30

Core charge stays the same... and increases...

Answer 30

- Down a group - Across a period (L-R)

Question 31

Nuclei- valence electron distance stays the same... and increases...

Answer 31

- Across a period (L-R) - Down a group

Question 32

Atomic radius

Answer 32

- Measurement for the size of atoms - From nucleus to valence electrons

Question 33

Atomic radius decreases

Answer 33

Across a period

Question 34

Atomic radius increases

Answer 34

Down a group

Question 35

Ionisation

Answer 35

The process of removing electrons from an atom to become an ion

Question 36

First ionisation energy

Answer 36

The energy which is required to remove the first valence electron from an atom in the gas phase

Question 37

Ionisation energy

Answer 37

- The energy required to remove one electron from an atom of an element in the gas phase - The stronger the valence electron is held the more ionisation energy is needed

Question 38

First ionisation energy

Answer 38

The energy required to remove the first valence electron from an atom in the gas phase

Question 39

Ionisation energy increases

Answer 39

Across a period

Question 40

Ionisation energy decreases

Answer 40

Down a group

Question 41

Successive ionisation energy

Answer 41

The energy required to achieve the sequential removal of electrons from an atom

Question 42

Metallic character

Answer 42

How closely an element exhibits the properties commonly associated with metals (mostly that they lose an electron to form a cation)

Question 43

Electronegativity

Answer 43

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

Question 44

Electronegativity increases

Answer 44

Across a period

Question 45

Electronegativity decreases

Answer 45

Down a group

Question 46

What can electronegativity predict

Answer 46

The type of bonding

Question 47

Ground state

Answer 47

Lowest energy level of the atom

Question 48

Excited state

Answer 48

The higher energy state of the atom

Question 49

How is absorbed energy emitted

Answer 49

Electromagnetic radiation

Question 50

Electromagnetic radiation examples

Answer 50

- X-ray - Visible light - Radio waves

Question 51

What are different colours of lights

Answer 51

Electromagnetic radiation of varying wavelengths and frequencies

Question 52

Spectroscopy

Answer 52

The study of the interaction between matter and electromagnetic radiation

Question 53

Limitations of the flame test

Answer 53

- Qualitative data only - Only a small range of metals are able to be detected - Metals in low concentrations can be difficult to observe - Mixtures of metals produce confusing results

Question 54

Atomic Absorption Spectroscopy

Answer 54

The direct relationship between the concentration of the sample being analysed and the light it absorbs

Question 55

Positives of the AAS

Answer 55

- Provides both qualitative and quantitative data - More than 70 elements can be analysed - Can detect very low amounts of concentration - Highly selective > regularly used with mixtures