1.1 - Atomic - Structure - Niveen
1.1 - Atomic - Structure - Niveen
1.1 - Atomic - Structure - Niveen
Objectives:
Objectives of 1.1
• Describe the empty- space structure of the
atom
• List the characteristics of each fundamental
particle of the atom
First Activity: Diagnostic Quiz on Socrative (5 min)
Third Activity:
Total Time: 15 minutes
Mission: Form groups A, B, C, D, E and F
• Person 1 and 2: explain your findings to the your group members (5 min)
• Person 3: explain your understanding to the your group members (5 min)
• Person 4: explain your understanding to the your group members (5 min)
All substances are made from very tiny particles called atoms.
.
Copper is an
element made up of
copper atoms only.
Carbon is an
element made up of
carbon atoms only.
How small is an atom?
Atoms are extremely small – they are about 0.00000001 cm
wide.
To make an atom the size of a football it would have to be
enlarged by about 3,000,000,000 times.
N X3,000,000,000
A radiaoactive
source emits a beam
of positively charged
α
particles towards a
gold foil.
Most of the α pass
through without
deviation leaving a
fuorecent spot on a
screen. The rest α
particles are largely
deviated due to
repulsion.
Results of foil experiment if Plum Pudding model
had been correct.
Actual Results.
Scientist Information Model
Mass Number A
ZX
Element Symbol
Atomic Number
1 2 3
1H 1H (D) 1H (T)
235 238
92 U 92 U
What’s the atomic number?
What are the atomic numbers of these elements?
11 26 50 9
What’s the mass number?
What are the mass numbers of these elements?
23 56 119 19
What’s the mass number?
How many neutrons in each of the following?
12 30 69 10
Atoms and electrical charge
An important feature of subatomic particles is their electrical
charge:
Particle proton neutron electron
Charge +1 0 -1
Atoms have equal numbers of protons and electrons, which
means their overall charge is zero.
9 protons = +9
9 electrons = -9
10 neutrons = 0
Total charge = 0
V- Isotopes of chlorine
What do you notice about these atoms of chlorine?
17 protons 17 protons
18 neutrons 20 neutrons
17 electrons 17 electrons
Isotopes of carbon
What do you notice about these three carbon atoms?
mass number is
different
LecturePLUS Timberlake 29
Atomic Mass
The atomic mass of an element
• is listed below the symbol of each element
on the periodic table. Na
• gives the mass of an “average” atom of 22.99
each element compared to 12C.
30
Atomic Mass for Cl
The atomic mass of chlorine is
• due to all the Cl isotopes.
• not a whole number.
• the average of two isotopes:
35Cl and 37Cl.
31
Calculating Atomic Mass for Cl
35Cl has atomic mass 34.97 amu (75.76%) and 37C
has atomic mass 36.97 amu (24.24%).
• Use atomic mass and percent of each isotope to
calculate the contribution of each isotope to the
weighted average.
34.97 x 75.76 = 26.49 amu
100
36.97 x 24.24 = 8.961 amu
100
• Sum is atomic mass of Cl 35.45 amu
32
Atomic Mass of Magnesium
The atomic mass of Mg
• is due to all the Mg
isotopes.
• is a weighted average.
• is not a whole number.
33
Calculating Atomic Mass Mg
Isotope Mass Abundance
34
Calculating Atomic Mass
35
Learning Check
1- Using the periodic table on the second slide,
specify the atomic mass of
each element.
A. calcium __________
B. aluminum __________
C. lead __________
D. barium __________
E. iron __________
36
Learning Check
38
Multiple-choice quiz
Solution of 1-
40
Solution of 2
2- 69Ga
68.926 amu x 60.10 = 41.42 amu (from 69Ga)
100
71Ga
41