1. Atoms, Elements and the Periodic Table
Chapter 2 Lesson 3

2. Objectives To identify particles in an atom
Recognize elements and their symbols
Locate metals and non-metals in the periodic table
To understand what a subscript means when following a chemical symbol

3. Substances A substance is NOT a mixture.
Substances have definite composition and definite properties.
Can be either an element or a compound.

4. Atoms All matter is made of tiny particles called atoms.
Atoms are made of 3 different particles:
Protons
Neutrons
Electrons

5. Atoms Continued… Protons- Have a positive charge
Neutrons- Have no charge, they are neutral
Electrons- Have a negative charge
Protons and neutrons are packed in a very small nucleus, while electrons move around the nucleus in a much bigger space

6. Atoms Continued…
When atoms bond (combine chemically), electrons are ALWAYS involved.
Sometimes two atoms share electrons
Sometimes atoms give electrons away to other atoms.
***A chemical bond forms when two atoms share or transfer electrons.

7. Atoms Continued…
A neutral atom has the name number as protons and electrons.
Lithium (Li) has 3 electrons, 3 protons and 4 neutrons.
Electrons have a -3 charge, Protons have a +3 charge which makes the atom neutral.
The positive and negative charges cancel each other out

8. Elements Substances made only from one kind of atom.
Simplest forms of matter
Ex: oxygen, helium, calcium, etc.

9. What makes atoms different?
Atoms are different because of the number of protons in the atom.
Ex: Any atom with 8 protons is an oxygen atom.
The number of protons in an atom is called the atomic number.
Every element has its own atomic number.

10. Elements Continued…
An atom is the smallest particle of an element that has the properties of that element.
90 of the 111 named elements occur in nature.
The symbol of an element consists of one or two letters; the first letter is ALWAYS capitalized.

11. The Periodic Table Gives the names and symbols for every element.
The elements are placed according to atomic number.
Elements are also placed according to their electron arrangment.

12. The Periodic Table Cont…
Two main sections;
Metals
Shiny solids
Can conduct, or transfer heat and electricity
Non-metals
Gases or dull solids
Do not conduct heat or electricity well