Chemistry Review (part 1)

SCH 4UI Exam Review Unit #1 – Atomic Structure

1. 
   Explain how the lines of the line emission spectrum relate to the energy levels in the Bohr model of the atom.
   

The energy released by the electrons as they fall from a higher energy level to a lower energy level is represented by the lines of the emission spectrum. (only the ones falling to the second energy level are visible to us)

2. 
   List the four quantum numbers and explain how they are represented in an energy level diagram
   

The Principal Quantum Number (n) - relates primarily to the main energy level of an electron. The larger the n the higher the energy.

The Secondary Quantum Number (ℓ) (Angular Momentum or Azimuthal Quantum Number) - distinguishes orbitals of a given n that have different shapes, the different subshells are usually denoted by the following letters

ℓ	0	1	2	3	4
letter	s	p	d	f	g

The Magnetic Quantum Number (m_ℓ) - distinguishes orbitals that have the same n (energy) and ℓ (shape), but different orientation in space.

The Spin Quantum Number (m_s) – distinguishes the direction the electron is spining

3. 
   State the Pauli Exclusion Principle - No two electrons in an atom can have the same four quantum numbers. An orbital can hold at most two electrons, and then only if the electrons have opposite spins.
   

Aufbau Principle - each electron occupies the lowest energy orbital available

Hund’s Rule Whenever electrons are added to orbitals of the same energy sublevel, each orbital receives one electron before any pairing occurs. When electrons are added singly to separate orbitals of the same energy, the electrons must all have the same spin.

4 and 5. Draw the energy level diagram and write the electron configuration for the neutral atom and any ions of the following elements

	neutral atom	ion
oxygen	O 1s^2 2s^2 2p^4	O^2- 1s^2 2s^2 2p^6
magnesium	Mg 1s^2 2s^2 2p^6 3s^2	Mg^2+ 1s^2 2s^2 2p^6 3s^0
silver	Ag [Kr]5s^14d^10	Ag^1+ [Kr]5s^04d^10
lead	Pb [Xe] 6s^2 4f^14 5d^10 6p^2	Pb^2+ [Xe] 6s^2 4f^14 5d^10 6p^0 Pb^4+ [Xe] 6s^0 4f^14 5d^10 6p^0
mendelevium	Md [Rn]7s^2 5f^13	don’t need to do

6. State the Heisenberg uncertainty principle - It is impossible to know simultaneously, with absolute precision, both the position and the momentum of a particle such as an electron.

8. 
   Explain the difference between the following
   

1. 
   covalent and co-ordinate covalent – in a covalent bond each atom donates one of the shared electrons, in a co-ordinate covalent bond on atom donates both of the shared electrons
   
2. 
   σ and π bonds – a σ bond in formed by the end to end overlap of 2 orbitals, a π is formed by the side by side overlap of two p orbitals
   
3. 
   single double and triple bonds – a single bond is made up of one σ bond, a double bond is made up of one σ bond and one π bond and a triple bond is made up of one σ bond and two π bonds
   

8. 
   Draw the Lewis diagram for the following
   

   a. PO4^3-	b. ClO2^-
   O O—P—O O	O—Cl—O

9. 
   Give the VSPER shape and the hybridization of the central atom for the following
   

1. 
   CF₄ – tetrahedral – sp³
   
2. 
   NH₃ – trigonal pyramidal – sp³
   
3. 
   BeCl₂ – linear - sp
   
4. 
   NH₄⁺ - tetrahedral – sp³
   
5. 
   CO₂ – linear - sp
   
6. 
   SO₂ – linear - sp
   
7. 
   SF₆ – octahedral – sp³d²
   
8. 
   XeCl_{6 –} n/a
   
9. 
   XeBr₄ – square planar – sp³d²
   
10. 
    PCl₅ – trigonal bipyramial – sp³d
    
11. 
    AsBr₃ – T-shaped – sp³
    

8. 
   Determine if the molecules in question 10 are polar or non-polar
   

1. 
   non-polar
   
2. 
   polar
   
3. 
   non-polar
   
4. 
   n/a
   
5. 
   non-polar
   
6. 
   polar
   
7. 
   non-polar
   
8. 
   n/a
   
9. 
   non-polar
   
10. 
    non-polar
    
11. 
    polar
    

8. 
   This question has been removed.
   
9. 
   Identify the following compounds as ionic, metallic, molecular or covalent network
   

1. 
   carbon dioxide - molecular
   
2. 
   magnesium chloride - ionic
   
3. 
   butanol - molecular
   
4. 
   silicon dioxide – covalent network
   
5. 
   iron - metallic
   
6. 
   sodium chloride - ionic