ATOM BASICS

2

Atomic Theory

Atoms are building blocks of

elements

Similar atoms in each element

Different from atoms of other

elements

Two or more different atoms bond in

simple ratios to form compounds

3

Subatomic Particles

Particle Symbol Charge Relative

Mass

Electron e- 1- 0

Proton p+ + 1

Neutron n 0 1

Atomic Structure

Atoms are composed of 2 regions:

NucleusElectron

Cloud

Atomic Structure

Nucleus: the center of the atom that contains the mass of the atom

Electron cloud: region that surrounds the nucleus that contains most of the space in the atom

6

Atomic Number

Number of protons in an atom

All atoms of an element have the same number of protons

7

Atomic Number -Periodic Table

11Na

Atomic NumberSymbol

8

Atomic Number -Periodic Table

11Na

11 Protons

Sodium

9

Learning Check

State the number of protons for atoms of each of the following:

Nitrogen

10

Atomic Number -Periodic Table

7N

7 Protons

Nitrogen

11

Learning Check

State the number of protons for atoms of each of the following:

Sulfur

12

Atomic Number -Periodic Table

16S

16 Protons

Sulfur

13

Learning Check

State the number of protons for atoms of each of the following:

Barium

14

Atomic Number -Periodic Table

56Ba

56 Protons

Barium

15

Mass Number

Counts the number of protons and neutrons in an atom

Mass number= p+ + n0

16

Atomic Symbols

Show the mass number

and atomic number

Give the symbol of the

element

17

Atomic Symbols

Na

Mass number

Atomic number

11

23

18

Learning Check

Cl

Mass number

Atomic number

17

35

How many protons?

What is the element?

How many neutrons?

19

Learning Check

Cl

Mass number

Atomic number

17

35

What is the element?

Chlorine

20

Learning Check

Cl

Mass number

Atomic number

17

35

How many protons?

p = atomic # = 17

21

Learning Check

Cl

Mass number

Atomic number

17

35 How many

neutrons?

n0 = 35 (mass number– 17 (p+)

n0 = 18

22

Number of Electrons

An atom is neutral The net charge is zeroNumber of protons = Number of electrons

Atomic number = Number of electrons

23

Learning Check

O8

16

n0 =

p+ =

e- =

8

8

8

24

Learning Check

P15

31

n0 =

p+ =

e- =

1516

15

25

Learning Check

Zn

30

65

n0 =

p+ =

e- =

3035

30

26

IsotopesAtoms with the same

number of protons, but

different numbers of

neutrons. Atoms of the same element (same atomic number) with different mass numbers

27

IsotopesIsotopes of chlorine

35Cl 37Cl17 17

chlorine - 35 chlorine - 37

LecturePLUS Timberlake 28

Learning Check

Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms.

12C 13C 14C 6 6

6

#p _______ _______ _______

#n _______ _______

_______

#e _______ _______

_______

LecturePLUS Timberlake 29

Solution

12C 13C 14C

6 6 6

#p 6 6

6

#n 6 7 8

#e 6 6

6

30

Learning Check

An atom of zinc has a mass number of 65.

A. Number of protons in the zinc atom

B. Number of neutrons in the zinc atom

C. What is the mass number of a zinc isotope

with 37 neutrons? Draw its atomic symbol.

31

Learning Check

An atom of zinc has a mass number of 65.

A. Number of protons in the zinc atom

30

32

Learning Check

An atom of zinc has a mass number of 65.

B. Number of neutrons in the zinc atom

35

33

Learning Check

C. What is the mass number of a zinc isotope

with 37 neutrons? Draw its atomic symbol.

67 Zn

30

67

34

Learning Check

Write the atomic symbols for atoms with the following:

A. 8 p+, 8 n, 8 e-___________

B. 17p+, 20n, 17e- ___________

C. 47p+, 60 n, 47 e-___________

35

Solution

16OA. 8 p+, 8 n, 8 e- 8

B. 17p+, 20n, 17e- 37Cl 17

C. 47p+, 60 n, 47 e- 107Ag 47

36

Atomic Mass on the Periodic Table

11Na

22.99

Atomic Number

Symbol

Atomic Mass

37

Atomic Mass

Atomic mass is the weighted average mass of all the atomic masses of the isotopes of that atom.

BEAN BAGIUM

IONIon – charged particle that forms when an atom gains or loses one or more electrons

IONCation – positively charged particle when an atom loses electrons

protons(+) > electrons(-1)

CATION

Ca+2

protons(+) = 20electrons(-) = 18

IONAnion – negatively charged particle when an atom gains electrons

electrons(-) > protons(+)

CATION

N-3

protons(+) = 7electrons(-) = 10