October 29th, 2015

• Start Atomic Structure & Periodic Table

Bell Ringer

•Get homework out on your desk.

Today’s Purpose:

1. Describe the present model of the atom.

Matter and atoms

Matter:

• Anything that has mass and takes up space.

• All matter is made up of atoms.

Matter and atoms

Atom:

•Basic building block of matter

•Cannot be broken down further without changing the properties of that element

•The smallest unit of an element

Different types of atoms are called elements.

All matter is made of the atoms of approximately 118

elements.

Iron 5%

Earth’s Crust

Oxygen47%

Silicon28%

Aluminum 8 %

Other12%

Humans

Other 3%

Nit rogen 3%

SOURCE: CRC H andbook of Chemistr y and Physics

Oxygen61%

Carbon23%

Hydrogen 10%

Atom Concentrations by Mass

Chemical symbols

A chemical symbol is an abbreviated way to write the name of an element.

For example:

C =

H =

Fe = Iron

Hydrogen

Carbon

Chemical symbols

Chemical symbols always consist of one capital letter or a capital letter plus one or two

small letters.

C Cl CSCs

neutron

electron cloud

nucleus proton

Atoms are made of protons, neutrons, and electrons.

Nucleus – the central region of an atom where most of the atom’s mass is found in protons and neutrons.

Atoms are mostly empty space.

The radius of a atom is about 100,000 times larger than the radius of its nucleus.

If a basketball represented a nucleus…that atom would have a radius of 7.5 miles!

Protons: Positive (+) charge, mass = 1, indicates identity of atom

Neutrons: Neutral (0) charge, mass = 1

Electrons: Negative (-)charge, mass = 1/2000

Found inside

nucleus

Found outside nucleus

B5

Boron

Atomic Number = Number of protons

Boron has 5 protons

Mass Number = Protons + Neutrons

Protons = 7

+ Electrons = ?

N+3

7

+3

4

Charge = +3

Protons = 35

+ Electrons = ?

Br-1

35

36

Charge = -1

Protons = 25

+ Electrons = ?

Mn25

25

Charge = 0

Matter and atoms

Nucleus (+ charge)

Electrons (- charge)

- “orbit” the nucleus

Proton (+)

Neutron (No charge)

Models of the atom

Assignments

• Book reading chapter.

• Atomic Structure (ws)

• Quiz on elements Wednesday, November 4th