Arrangement of electrons

Question 1

Bohr’s study of spectra

Answer 1

1. Light passed through a glass prism and a series of narrow, coloured lines are observed.
2. The emission spectrum of hydrogen consists of a series of lines of different colours. Each line corresponds to light of a different frequency.

Question 2

Flame tests

Answer 2

1. Use a damp wooden splint to hold a sample of each salt.
   Lithium - Crimson (Crimson antidepressant)
   Potassium - Lilac (Purple bananas)
   Barium - Green (green oil)
   Strontium - Red (red fireworks)
   Copper - Blue-green (Blue-green tarnished ring from Shein)
   Sodium - Yellow (Yellow chips)

Question 3

Use of emission spectra

Answer 3

Sodium in street lamps (Gives yellow colour)
Gives colour to fireworks (when mix certain salts with certain metals)

Question 4

The Bohr theory

Answer 4

1. Electrons in an atom possess only a certain fixed amount of energy (quantum)
2. Proposed that electros orbit the nucleus like planets in a solar system

Question 5

An energy level

Answer 5

is defined as the fixed energy value that an electron in an atom may have

Question 6

The ground state

Answer 6

of an atom is one in which the electrons occupy the lowest energy level available

Question 7

The excited state

Answer 7

of an atom is one in which the electrons occupy the higher energy levels than those available in the ground state

Question 8

Atomic absorption spectrometry

Answer 8

1. Used to measure how much of a certain element is in a sample.
2. Dark lines on a coloured spectrum when white light is passed through a sample in its gaseous state.

Question 9

Principle behind the Atomic absorption spectrometry

Answer 9

1. Atoms of an element in the ground state absorb light of a particular wavelength that is characteristic of the element.
2. The amount of light absorbed by an element in solution is directly proportional to the concentration of the element.

Question 10

Energy sublevels

Answer 10

1. Energy transitions discovered when looking at emission spectra more closely, the lines produced from the emission spectra had smaller lines closer together.
2. The number of energy sublevels is the same as the number of main energy levels i.e. in the 2nd energy level there are 2 sublevels, in the 3rd energy level there are 3 sublevels etc.

Question 11

Energy sublevel

Answer 11

A group of atomic orbitals within an energy level, that all have the same energy.

Question 12

Wave nature of an electron

Answer 12

If the electron has a wave motion, then it cannot be travelling in a precise path at a fixed distance from the nucleus.

Question 13

Heinsenberg’s Uncertainty Principle

Answer 13

states that it is not possible to measure both the velocity and the position of an electron at the same time.

Question 14

Limitations of Bohr’s Theory

Answer 14

1. Only accounts for hydrogen atoms
2. Does not take into account the wave nature of the electron
3. Did not take into account the existence of sublevels

Question 15

Atomic orbitals

Answer 15

A region of space surrounding the nucleus of an atom in which there is a high probability of finding an electron.

Question 16

A sublevel

Answer 16

a subdivision of a main energy level and consists of one or more orbitals of the same energy

Question 17

s orbitals

Answer 17

1. All s orbitals are spherical in shape

Question 18

p orbitals

Answer 18

1. p orbitals are dumbbell-shaped and are aligned at right angles to each other along the x, y and z axes.