Date: 10-8-13 Day Plan:

› 1) Finish Isotope and Atom Packet› 2) Start History of an Atom

Opener : Look at the picture below. Exampling A) How are all of these atoms alike B) How are all of these atomsdifferent C) Explain what an Isotope is

Name Symbol Atomic # Z

Mass Number A

# of Neutrons

# of Electrons

Atoms & Their Isotopes – Paragraph #1 Entire world is composed of atoms Atoms are composed of

› Proton (charge +1) weigh 2000x more › Neutron (no charge) than electrons› Electron (charge -1)

Properties of an atom are determined by the number of P+, N0, and E-

Key Questions 1. The atomic number [Z] tells the reader

the number of protons 2. The mass number [A] tells the reader

the number of protons and neutrons.

3. The number of protons is equal to the number of electrons.

4. The electrical charge of an atom with an equal number of protons and electrons is neutral or no charge.

5. The protons and neutrons are located in the nucleus of an atom.

6. The two sodium isotopes have the same number of protons and electrons.

7. The two sodium isotopes have different number of neutrons.

Isotopes of an element Atom has the same number of protons

but a different number of neutrons Neutral atoms have equal number of

protons and electrons

Atomic Symbol Notation

A Mass Number (number of protons and neutrons)

X Atomic Symbol

Z Atomic Number (number of protons)

8. The following can distinguish an atom of one element from an atom of another element:› Mass the number of protons and

electrons› Atomic number the number of neutrons

Exercises 1. Similarities include:

› They are the same element› They each have 17 protons› They each have 17 electrons

2. Differences include:› They have different mass numbers.› Cl-35 has 18 neutrons› Cl-37 has 20 neutrons.

Name Symbol Atomic Number (Z)

Mass Number (A)

Number of Neutrons

Number of Electrons

Oxygen 16 8

8 16 8 8

7 7

3416

18

1 1

1 3

12 24

12 25

238 92

8436

84 36

O

S

Kr

Name Symbol Atomic Number (Z)

Mass Number (A)

Number of Neutrons

Number of Electrons

Oxygen 16 8

8 16 8 8

Nitrogen 14 7

7 14 7 7

Sulfur 3416

16 34 18 16

Hydrogen 11

1 2 0 1

Hydrogen 31

1 3 2 1

Magnesium 2412

12 24 12 12

Magnesium 2512

12 25 13 12

Uranium 238 92

92 238 146 92

Krypton 8436

36 84 48 36

O

N

S

H

H

Mg

Mg

U

Kr

Problems 1. The radius of a Cl nucleus is 4.0 fm,

and the radius of a Cl atom is 100 pm. How many times larger is the diameter of the Cl atom than the diameter of a Cl nucleus?

2. Two objects that have the same ratio of length.

1 fm = 1 x 10-15 m1 pm = 1 x 10-12 m

Problems 3. How many times larger is the

volume of the atom than the volume of the nucleus?

Volume = 4/3(pi)*r3

4. Use a periodic table to fill in the missing information in the following table.

Name Symbol

Atomic Number Z

Mass Number A

Number of Neutrons

Number of Electrons

Oxygen 16 O 8

8 16 8 8

7 734 S16

18