Atomic Structures

Question 1

Recall Bohr’s Theory

Answer 1

The Bohr theory states that the structure of an atom is a small nucleus of protons and neutrons surrounded by circulating electrons

• Each shell or energy level could hold a maximum number of electrons
• The energy of levels became greater as they got further from the nucleus and electrons filled energy levels in order

Question 2

Recall the Aufbau Principle

Answer 2

Electrons enter the lowest available energy level

Question 3

Recall Pauli’s Exclusion Principle

Answer 3

Two electrons can go in each orbital, providing they are of opposite spin

Question 4

Recall Hund’s Rule of maximum multiplicity

Answer 4

When in orbitals of equal energy, electrons will try to remain unpaired

• Placing two electrons in one orbital means that, as they are both negatively charged, there will be some electrostatic repulsion between them
• Placing each electron in a separate orbital reduces the repulsion and the system is more stable

Question 5

Describe nuclear symbol notation [isotope notation]

Answer 5

A/Z[X] or X-A
For example: 14/6[C] or carbon-14

• A = Mass number (Z + number of neutrons)
• Z = Atomic number (number of protons)
• X = Chemical symbol for the element

Question 6

Recall the [4] different sub-levels

Answer 6

• s sub-shell: 1 orbital, 2 electrons, sphere shape
• p sub-shell: 3 orbitals, 6 electrons (2 in each orbital), dumbbell shape
• d sub-shell: 5 orbitals, 10 electrons (2 in each orbital)
• f sub-shell: 7 orbitals, 14 electrons (2 in each orbital)

Question 7

Define orbital

Answer 7

A region in space where one is likely to find an electron

Question 8

Describe protons

Answer 8

A subatomic particle with a positive charge found in the nucleus of an atom

Question 9

Describe neutrons

Answer 9

A subatomic particle with a neutral charge found in the nucleus of an atom

Question 10

Describe electrons

Answer 10

A subatomic particle with a negative charge found in the orbitals surrounding the nucleus of an atom

Question 11

Describe and explain ions

Answer 11

An atom or molecule with a charge due to an unbalance of electrons and protons in an attempt to fill the atom’s outermost shell

• More electrons = negative charge
• Less electrons = positive charge

Question 12

Recall the electron configuration of Mg

Answer 12

1s² 2s² 2p⁶ 3s²

Question 13

Recall the electron configuration of Cr

Answer 13

1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵
Cr is an exception: To become more stable 1 electron in the 4s sub-shell moves to the 3d sub-shell

Question 14

Recall the electron configuration of Cu

Answer 14

1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰
Cu is an exception: To become more stable 1 electron in the 4s sub-shell moves to the 3d sub-shell

Question 15

Recall the electron configuration of Kr

Answer 15

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶