Chapter 3 - PT

Question 1

What is electron shell

Answer 1

The region of space the electron occupies is known as electron shell

Question 2

What is energy Level

Answer 2

The shells corresponds with a fixed quantity of energy and energy electrons occupying that shell possesses the same amount of energy, hence referred to as energy levels

Question 3

Outer most shell

Answer 3

Outer most shell is the valence shell, electrons in here are called valence electrons

Question 4

What is the octet rule

Answer 4

Octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell.

2,8,8,16

Question 5

What does the group do

Answer 5

• organises elements according to similar properties
• columns
• group number shows how many outer shell valence electrons are there

Question 6

What do periods do

Answer 6

• rows

- period = number four electron shell in atom structure

Question 7

What is core charge and how to calculate

Answer 7

Core charge = number of Protons In nucleus- number of total inner shell electrons (not valence)

• core charge or effective nuclear charge is the resultant attractive force experienced by valence electrons once the impact of the shielding effect provided by the electrons in inner shells is taken to account
• increases from left to right
• stays constant down a group

Question 8

What is atomic radius

Answer 8

Atomic radius is the measurement used for the size of atoms
- distance from the nucleus to valence shell electrons

• decreases from left to right as the nucleus strongly attracts the valence electrons closer inwards
• increases down a group because the number of electron shells increases

Question 9

What is first ionisation energy

Answer 9

The first ionisation energy is the energy required to remove the first valence electrons from an atom of a element in the gas phase

• energy decreases down the group because number of shells increases therefore the valence electrons are less attracted to the nucleus
• energy increases across the periods because shells remain constant and are strongly attracted to nucleus, therefore more energy is required

Question 10

What is successive ionisation energy

Answer 10

The energy required to achieve the sequential removal of electrons from atom is known as Successive Ionisation energy

Question 11

Metallic character

Answer 11

Describes how closely an element exhibits the properties commonly associated with a metal - loss electron and become a cation

• increases across

Question 12

What is electronegativity

Answer 12

It is the ability of an element to attract electrons in a covalent bond towards itself

Down groups - decreases - core charge constant and valence electrons are less attracted to nucleus, therefore further away

Increases across periods, number of shells is constant, core charge increases and valence electrons are more strongly attracted of nucleus therefore electronegativity increases

Question 13

Explain Quantisation ( ground state, excited state and process )

Answer 13

The quantisation of energy describes that the energy of electrons only exits at discrete levels.

The lowest level of energy state of an atom is called the ground state.

When energy is given to electron (thermal or light ), is absorbs it and jumps to from energy level shell to an associated higher energy level. This electron is elevated in a higher energy level state called excited state.

The range of colours representing the types of energy absorbed by electrons moving from higher energy levels are called absorption spectra.

When the electron falls from a higher energy level to lower energy level, it emits the absorbed energy in the form of light.

The range of colours of light emitted by electrons moving into lower energy levels is called emission spectra.

Each element has its own unique absorption/ emission spectrum

Question 14

Explain the Atomic Absorption Spectroscopy - finds amount of element present

Answer 14

1. ) A hollow cathode lamp containing part of the element being tested is made. The sample is vaporised atomising the substance in sample.
2. ) Light of specific wavelength from lamp passes through vaporised sample. Only the element being tested will absorb the specific wavelength of the lamp. This is because energy levels of other atoms are different.
3. ) light passes through the sample, and what remains passes through a slit.

4.) it enters the monochromator which selects only one wavelength
for analysis

5. ) The number produced when detected measures intensity of light - light Absorbance value.
6. ) To measure the sample, it is compared to known samples. A calibration curve is produced.