6.7 THE STRUCTURE OF

THE ATOM(p.234-240)

INSIDE THE ATOM:

• The _____ is the smallest particle of an element that has the same properties of the element. • Atoms do not have a CHARGE.• The atom is composed of many smaller ___________ particles. • 3 Main Types of Subatomic Particles: __________ and __________, which make up the ________ and ___________, which move in specific regions around the nucleus.

atom

subatomic

protonsneutrons nucleus electrons

TERMINOLOGY

• ________________: The number of protons in the nucleus of an atom. This identifies an atom as a particular element (the # of protons never changes).

• ______________: the ________ mass of the _________ occurring isotopes of an element.• The sum of the number of protons & neutrons in an atom.• Protons and neutrons contribute nearly all the mass

of an atom.

Atomic Number

Atomic Mass naturallyaverage

ATOMIC MASS

•Atomic Mass refers to the “weight” of the atom.• It is derived at by adding the number of protons with the number of neutrons.

HThis is a helium atom. Its atomic mass is 4 (protons plus neutrons).

What is its atomic number?

TERMINOLOGY

• _______________________: the number of rings around the nucleus that contain the electrons. (Period Number).

• _____________: The electrons in the outermost shell (Group Number)

• ___________: The outermost shell

Valence Electron

Valence Shell

Orbits / Shells / Energy Levels

Subatomic Particle

Charge Location Relative Mass

Protons  

   

Neutrons  

   

Electrons  

   

+’ve  Nucleus 1 AMU

Neutral  Nucleus 1 AMU

-‘ve Orbitals /

shells 1/2000* *

ATOMIC MASS UNIT (AMU)

•The unit of measurement for an atom is an AMU. It stands for atomic mass unit.•One AMU is equal to the mass of one proton.

ATOMIC MASS UNIT (AMU)

• There are 6 X 1023 or 600,000,000,000,000,000,000,000 AMU’s in one gram.• Remember that electrons are 2000 times smaller than one AMU.

Key TermsTry to find the following on the image…

• Nucleus• Protons• Neutrons

• Electrons• Orbits / shells /

energy levels• Valence Shell• Valence Electron

12

4

3

Energy LevelsValence

Electrons

Valence Shell

Lets See

What You

Know

Fill in the diagram on the following page… you MUST know all of these

terms….

REPRESENTING ELEMENTS:• The symbols that are used to represent the elements are the same throughout the world – the system is international.

• A common notation that scientists use to represent atoms of elements is called the _______________ ____________ ______________, which includes the _______ ___________ and ________ _____________ of an atom of an element.

StandardAtomic Notation Atomic

Number Atomic Mass

Review…. # of… in an ATOM of Carbon

Protons =

Neutrons =

Electrons =

Overall Charge =

# of Shells =

# of Valence Electrons =

? 3

? 4

? 2

? 5

? 1

REPRESENTING ATOMS:

•The Bohr-Rutherford model is a convenient way of representing the atomic structure of an element.•How to draw a Bohr-Rutherford Diagram: PAGE 236

EXAMPLES – FROM CLASS NOTE

• Potassium (K) 2-8-8-1 Sodium (Na) 2-8-1Hydrogen (H) 1 Oxygen (O) 2-6 • Carbon (C) 2-4 Silicon (Si) 2-8-4 Magnesium (Mg) 2-8-2 Aluminum (Al)

2-8-3 • Chlorine (Cl) 2-8-7 Argon (Ar) 2-8-8 Boron (B) 2-3 Calcium (Ca) 2-

8-8-2

• Lithium (Li) 2-1 Sulfur (S) 2-8-6 Neon (Ne) 2-8

LEWIS DOT DIAGRAM

• Simply show the number of valence electrons. • No reference to

number of shells/orbits/energy levels

HW QUESTIONS

•Pg 240

•Q 1-8