Notes: Subatomic Particles

CW: Graphic Organizer

H: An Atom

Subatomic ParticlesDecember 8, 2008

Objectives

1. Describe three subatomic particles

2. Define amu, atomic mass, atomic number, isotope

1. The Latin word atomos, is the basis for the word atom. What does the word atomos mean?

A. nucleus

B. indivisible

C.small

2. Indirect evidence about an object is evidence gathered

A. by reading a textbook

B. using your senses

C. without any experimenting

3. Rutherford’s model of the atom is similar to

A. the solar system

B. raw chocolate chip cookie dough

C. a peach

What is an atom? the smallest unit

of matter that keeps the identity of the element

electron

neutron

proton

Nucleus

Electron Cloud

3 subatomic particles

Protons

Positive charge

Found in the nucleus

Mass of 1 AMU (atomic mass unit)

Atomic Number

This number indicates the number of protons in an atom

The number of protons identifies the atom.

Neutrons

No charge

Found in the nucleus

Mass of 1 AMU (atomic mass unit)

Mass Number

© Addison-Wesley Publishing Company, Inc.

= protons + neutrons

Isotopes Atoms of the same element with different

mass numbers.

C126

Mass #

Atomic #

Hyphen notation: carbon-12

It’s the Isotopes!

Periodic Table

Electrons

•Negative Charge

•Found in energy levels outside the nucleus

•Mass of 1/1836 AMU (almost nothing!)

IonNeutral atom - The number of electrons

= number of protons.

Ion - The number of electrons is different from the number of protons. (charged atom)

PRACTICE PROBLEMS

15N # protons = ____ # neutrons= ____ #electrons = ___

35P # p = ____ # n= ____ #e- = ___

62Cu2+

# p = ____ # n= ____ #e- = ___

76Se3-

# p = ____ # n= ____ #e- = ___

7 8 7

15 20 15

29 33 27

34 42 37

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 _______ _______ _______

Solution

12C 13C 14C 6 6 6

#p 6 6 6

#n 6 7 8

#e 6 6 6

Quick Review: The three subatomic particles are

proton, neutron and electron Protons are positively charged,

electrons are negative, neutrons are neutral

When an electron is lost or gained, the atom becomes an ion.