This document discusses chemical characteristics and properties. It defines a chemical change as when two or more substances unite or break apart chemically, resulting in a new substance with different properties than the original. It also defines elements, compounds, atoms, and molecules. Atoms are made up of protons and neutrons in the nucleus and electrons orbiting the nucleus. The periodic table arranges elements by their atomic number and symbol.

1. 7 TH GRADE CHAPTER 4 LESSON 2 Pgs. 134-140 For Student Use Only

2. CHEMICAL CHARACTERISTICS Chemical Properties: The properties that describe how a substance changes while it is being converted into something else Chemical Change: When two or more substances unit or break apart chemically After a chemical change the properties of the new substance are different from the original properties

3. CHEMICAL CHARACTERISTICS Microscopic Matter: Element= simplest type of substance All elements are made of atoms Atoms= smallest particles of matter An element cannot be broken down into anything smaller than one particular kind of atom Compound= a new substance formed from the chemical union of two or more elements

4. CHEMICAL CHARACTERISTICS Matter: Compounds differ from each by the ratio of atoms Examples: H 2 O H 2 O 2 Chemical Formula: The written way to show compounds Chemical Reaction: The process of forming a chemical bond

5. CHEMICAL CHARACTERISTICS Petite Particles: Atoms were thought to be the smallest particles for a long time Atoms are made up of particles: In the Nucleus: Protons= positively charged particles Nuetrons= no charge or neutral Atomic Number= number of protons in the nucleus Electrons= outside nucleus and have a negative charge Size must be written in Scientific Notation (Get rid of zeros) Atomic Mass= number of protons and neutrons together, always written as a whole number

6. CHEMICAL CHARACTERISTICS The Atom: Electrons orbit in shells 1 st shell= 2 electrons 2 nd shell= 8 electrons 3 rd shell= 18 electrons 4 th shell= 32 electrons A stable atom: Equal number of protons and electrons Has no charge

7. CHEMICAL CHARACTERISTICS Atom Classification: Molecule: When 2 or more atoms are chemically united Can be different atoms Can also be same atoms Chemical Symbols: Each element has a symbol Symbols have one, two, or sometimes three letters Elements are arranged by atomic number and symbol in the periodic table of elements Periodic Table of Elements: Designed by Dmitri Ivanovich Mendeleev

8. CHEMICAL CHARACTERISTICS