ch. 4.2 - atomic structure i. subatomic particles (p.113 - 114)

Ch. 4.2 - Atomic Structure

I. Subatomic Particles(p.113 - 114)

Subatomic Particle Properties

Particle Symbol Location Charge Relative Mass (amu)

Actual Mass (g)

electron

proton

neutron

e-

p+

n0

Electron cloud

nucleus

nucleus

–

+

0

1/1840

1

1

9.11 x 10-28

1.67 x 10-24

1.67 x 10-24

approx 0

Symbols

Elements are listed by their chemical symbols

Symbols are usually either one capital letter like C for Carbon, or one capital and one lowercase letter like Ne for Neon

Periodic Table

The periodic table gives much information we need to learn more about the atom of each element

Atomic Number

Atomic number = # of protons in an atomWhole number shown on periodic tablePeriodic table is arranged by atomic

number

Atomic Mass

The average atomic mass is the number at the bottom of this square

Found by averaging the natural abundances of its isotopes

Weighted average

Atom Math

Atomic Number

Symbol

Element Name

Atomic Mass

Atom Math

Protons Electrons

Protons Neutrons

# n0 = Atomic mass – Atomic number

Subatomic Particles

POSIT IVECHARG E

PROT ONS

NEUT RALCHARG E

NEUT RONS

NUCLEUS

NEG AT IVE CHARG E

ELECT RONS

AT OM

Most of the atom’s mass.

NUCLEUS ELECTRONS

PROTONS NEUTRONS NEGATIVE CHARGE

POSITIVE CHARGE

NEUTRAL CHARGE

ATOM

QUARKS#n0 = Atomic mass- Atomic #

equal in a neutral atomAtomic Number

equals the # of...

Subatomic Particles

Quarks component of

protons & neutrons

6 types

3 quarks = 1 proton or 1 neutron

He

Ch. 4.3 - Atomic Structure

II. How Atoms Differ (p. 114 - 121) Mass Number Isotopes Relative Atomic Mass Average Atomic Mass

A. Mass Number

mass # = protons + neutrons

always a whole number

NOT on the Periodic Table!

© Addison-Wesley Publishing Company, Inc.

B. Isotopes

Atoms of the same element with different numbers of neutrons

C126

Mass #

Atomic #

Isotope notation:

Isotope name: carbon-12

Element name Mass #

B. Isotopes

© Addison-Wesley Publishing Company, Inc.

B. Isotopes

Chlorine-37 atomic #:

mass #:

# of protons:

# of electrons:

# of neutrons:

17

37

17

17

20

Cl3717

Isotope notation:

Natural Abundances of Isotopes

Most elements are found as mixtures of isotopes

Relative abundance of each isotope is the same in each source

C. Relative Atomic Mass

12C atom = 1.992 × 10-23 g

1 p = 1.007276 amu

1 n = 1.008665 amu

1 e- = 0.0005486 amu

© Addison-Wesley Publishing Company, Inc.

atomic mass unit (amu)

1 amu = 1/12 the mass of a 12C atom

D. Average Atomic Mass

weighted average of all isotopeson the Periodic Tableround to 2 decimal places

100

(%)(mass(mass)(%) )

Avg.AtomicMass

Avg.AtomicMass

D. Average Atomic Mass

EX: Calculate the avg. atomic mass of oxygen if its abundance in nature is 99.76% 16O, 0.04% 17O, and 0.20% 18O.

100

(18)(0.20)(17)(0.04))(16)(99.76 16.00amu

Avg.AtomicMass

D. Average Atomic Mass

EX: Find chlorine’s average atomic mass if approximately 8 of every 10 atoms are chlorine-35 and 2 are chlorine-37.

100

(37)(20)(35)(80)35.40 amu