Atomic Number

1
Atomic Number

• Number of Protons

2
Mass Number

• Number of Protons Neutrons

3
12C

• Left Superscript mass number

6
4
12C

• Left Subscript atomic number

6
5
80Br

• 35

35
Atomic Number ?
6
20Ne

• 20

10
Mass Number ?
7
27Al

• 27

13
Mass Number ?
8
40Ca

• 20

20
Atomic Number ?
9
of electrons in a neutral atom?

• Neutral atoms have the same number of electrons
  and protons.

10
Isotope

• Atoms of the same element with a different of
  neutrons

11
Characteristics of Proton

• Charge 1, mass 1 amu, location inside
  nucleus

12
Characteristics of Neutron

• Charge 0, mass 1 amu, location inside
  nucleus

13
Characteristics of Electron

• Charge -1, mass 1/1836 amu or 0.0005 amu,
  location outside nucleus

14
Ion

• An atom that has gained or lost electrons so
  carries charge

15
Positive Ion

• An atom that has LOST electrons

16
Negative Ion

• An atom that has GAINED electrons

17
Charge

• protons - electrons

18
Nucleons

• Protons Neutrons

19
atom

• Smallest bit of an element that retains the
  properties of the element.

20
of neutrons

• Mass number atomic number

21
14C

• 8 neutrons
• 6 protons
• 6 electrons

6
of neutrons ? of protons ? of electrons
?
22
9Be

• 5 neutrons
• 4 protons
• 4 electrons

4
of neutrons ? of protons ? of electrons
?
23
40Ar

• 22 neutrons
• 18 protons
• 18 electrons

18
of neutrons ? of protons ? of electrons
?
24
15N

• 8 neutrons
• 7 protons
• 7 electrons

7
of neutrons ? of protons ? of electrons
?
25
24Mg

• Right superscript charge

2
12
26
15N

• 8 neutrons
• 7 protons
• 10 electrons (gained 3)

-3
7
of neutrons ? of protons ? of electrons
?
27
19F

• 10 neutrons
• 9 protons
• 10 electrons (gained 1)

-1
9
of neutrons ? of protons ? of electrons
?
28
16O

• 8 neutrons
• 8 protons
• 10 electrons (gained 2)

-2
8
of neutrons ? of protons ? of electrons
?
29
23Na

• 12 neutrons
• 11 protons
• 10 electrons (lost 1)

1
11
of neutrons ? of protons ? of electrons
?
30
24Mg

• 12 neutrons
• 12 protons
• 10 electrons (lost 2)

2
12
of neutrons ? of protons ? of electrons
?
31
27Al

• 14 neutrons
• 13 protons
• 10 electrons (lost 3)

3
13
of neutrons ? of protons ? of electrons
?
32
Nuclear Charge

• Charge on the nucleus only. Does not include the
  electrons.
• Always positive.
• Equals the number of protons.

33
Cation

• Positive ion

34
Anion

• Negative ion

35
Daltons Model

• Billiard Ball Model

36
Daltons model

• Atoms are hard, round, indivisible. They are
  solid uniform throughout.

37
Thomsons Model

• Plum Pudding Model

-
-
-



-
-

38
Thomsons model

• Atoms are divisible.
• They are solid but NOT uniform throughout.
• They contain and - charges.
• The charges are little particles.

39
Rutherfords Model

• Nuclear Model

-

-
-
40
Rutherfords model

• Atoms are divisible. Atoms are NOT solid. Atoms
  are NOT uniform.
• They contain and - charges.
• Most of the mass and all of the charge is
  concentrated in the nucleus of the atom.
• Most of the volume is empty space.

41
Rutherfords Experiment

• Shot a particles at gold foil.
• Most went through, so most of the atom is empty
  space.
• Some deflected back by small dense positive
  nucleus.

42
Bohrs Model

• Planetary Model

43
atomic mass

• The mass of the entire atom includes protons,
  neutrons, electrons. Expressed relative to the
  mass of a C-12 atom.

44
atomic mass unit

• 1 atomic mass unit ? 1/12 the mass of a C-12
  atom.
• or
• The C-12 atom has a mass of 12.000 . . . atomic
  mass units.

45
Average atomic mass

• The weighted average of the masses of the
  naturally occurring isotopes of an element.

46
Average atomic mass

1. Convert abundance to decimal format.
2. Multiply abundance factor by appropriate mass.
3. Sum

47
Quick check on average atomic mass calculation.

1. Final answer must be between the highest lowest
   masses.
2. Final answer will be closest to mass of most
   abundant isotope.

48
Calculate the average atomic mass of Cl. 75 is
Cl-35 and 25 is Cl-37.

• 75 .75 and 25 .25
• (.75) X 35 26.25
• (.25) X 37 9.25
• 26.25 9.25 35.5 avg. atomic mass of Cl
• Ans is between 35 37, but closer to 35.