1. Section 1: The Nature of Matter
Chapter 2
Section 1: The Nature of Matter

2. Objectives Identify the three subatomic particles.
Explain how all of the isotopes of an element are similar and how they are different.
Explain what chemical compounds are.
Describe the two main types of chemical bonds.

3. Life Depends on Chemistry
Everyday, materials are used in chemical reactions that take place in your body to keep you alive.

4. Atoms Basic units of matter Contain subatomic particles
Protons: + charge
Neutrons: no charge
Electrons: - charge
*Neutrons and protons form the nucleus

5. Nucleus Located at the center of the atom
Formed by strong forces that bind protons and neutrons together.

6. Electrons http://www.teachersdomain.org/asset/phy03_vid_atoms/
Negatively charged particles
1/1840 the mass of a proton
In constant motion in the space surrounding the nucleus

7. Atoms are Neutral
Equal number of protons and electrons

8. Elements
Element: pure substance that consists entirely of one type of atom.
Represented in one
or 2-letter symbols.
Atomic Number: represents # of protons

9. Isotopes
Atoms of the same element that differ in the number of neutrons they contain.
Have the same chemical properties as the element because they have = electrons.
Identified by their mass number: sum of protons and neutrons in the nucleus.

10. Radioactive Isotopes http://www. pbs
Have unstable nuclei
Break down at a constant rate over time
Used to determine age of rocks, treat cancer and kill bacteria.

11. Chemical Compounds
Substances formed by the chemical combination of two or more elements in definite proportions.
Identified by chemical formulas: ex. H2O

12. Chemical Bonds Hold atoms together
Formed by valence electrons (electrons on outer shell)
Two Types
Ionic
Covalent

13. Ionic One or more electrons are transferred from one atom to another.
The atom that gains or loses electrons are called IONS.

14. Covalent Electrons are shared between atoms.
MOLECULES are formed when atoms form covalent bonds.

15. Molecules
Smallest unit of most compounds.

16. Van der Waals Forces
Slight attraction that develops between oppositely charged regions of nearby molecules.
Geckos use theses forces to climb vertically.

17. Section 2-1 Questions Describe and draw the structure of an atom.
Why do all isotopes of an element have the same chemical properties? In what way do isotopes of an atom differ?
What is a covalent bond? An ionic bond?
What is a compound?

18. Video Clip