Ch. 4

1
Ch. 4

• Atomic model

2
I. Parts of an atom

• Protons positive charge
• Neutrons no charge
• Electrons negative charge
• 1. in constant motion around nucleus of atom
  travel in orbitals, or shells

3
II. Atomic Shells

• Atomic number - of protons in the nucleus of an
  atom
• Atomic mass - of protons and neutrons in the
  nucleus
• Example for Scandium atom
• atomic of p ___
• p e- ___
• atomic mass atomic n0 ___

21 Sc 45.0
4
II. Atomic Shells

• Atomic number - of protons in the nucleus of an
  atom
• Atomic mass - of protons and neutrons in the
  nucleus
• Example for Scandium atom
• atomic of p 21
• p e- 21
• atomic mass atomic n0 24

21 Sc 45.0
5
Electrons

• How do electrons fill the energy levels, or
  orbitals?

6
Quantum Numbers

• Four numbers that describe the shape of the
  cloud.
• Described using the variables n, l, m, s.

7
Quantum s

• n - tells the size and energy
• l - tells the shape spherical, barbell,etc.
• m - tells how the shape fits on the x, y, z axes
• s- tells about spin clockwise or counter
  clockwise.

8
n the Principle Quantum Number(Energy
Quantum )

• Corresponds to periodic tables horizontal row.

n 1
n 2
n 3
9
n the Principle Quantum Number(Energy
Quantum )

• Higher number, more energy
• higher number, bigger cloud
• 2n2 is how many electrons may have that energy (
  how many electrons can fill that orbital)

10
II. Atomic Shells

• Orbitals that electrons travel in
• 1st, 2nd, 3rd, 4th, 5th,6th
• Sublevels of orbitals ( quantum number l)
• 1. s can hold 2 electrons
• 2. p can hold 6 electrons
• 3. d can hold 10 electrons
• 4. f can hold 14 electrons

11
Quantum Number

• Keep in mind are probabilities of finding
  electrons in certain places doing certain
  things(spin).

• n what energy level (1, 2, 3, 4 . . .)
• l what sub-level (s, p, d, or f)
• m orientation of orbital (s1 p3 d5 f?)
• s which spin (only two possibilities up or down)

12
II. Atomic Shells

• Order of filling orbitals and subshells
• 1s
• 2s 2p
• 3s 3p 3d
• 4s 4p 4d 4f
• 5s 5p 5d 5f
• 6s 6p 6d 6f
• 7s 7p 7d 7f

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s
4f 5d 6p 7s 2 2 6 2 6 2 10
6 2 10 6 2 14 10 6 2 of
electrons
13
Draw atomic model
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s
4f 5d 6p 7s 2 2 6 2 6 2 1

of electrons
14
Pauli Exclusion Principle

• No two electrons ever have the same four quantum
  numbers in the same atom.