The Nature of Matter Chapter 2 Section 1

Atoms  All matter is made up of atoms.  Atoms are the smallest units of matter.  Atoms consist of two regions: Nucleus Nucleus Electron Cloud Electron Cloud

Subatomic Particles  There are 3 subatomic particles: Protons (positive charge) Protons (positive charge) Neutrons (neutral charge) Neutrons (neutral charge) Electrons (negative charge) Electrons (negative charge)  Protons and neutrons are in the nucleus.  Electrons are in the electron cloud.

More Chemistry Terms  Element—pure substance made up of only one type of atom Examples: gold, oxygen, iodine Examples: gold, oxygen, iodine  Compound—pure substance made up of two or more types of atoms in definite proportions Examples: H 2 O, CO 2, NH 3 Examples: H 2 O, CO 2, NH 3  Molecule—smallest unit of a compound

Chemical Bonds  Compounds are held together by chemical bonds.  There are two main types of chemical bonds: Ionic Bonds Ionic Bonds Covalent Bonds Covalent Bonds

Types of Bonds  Ionic Bonds Formed between metals and nonmetals Formed between metals and nonmetals Forms positive and negative ions Forms positive and negative ions Electrons are exchanged Electrons are exchanged  Covalent Bonds Formed between nonmetals and other nonmetals Formed between nonmetals and other nonmetals Electrons are shared Electrons are shared

Solutions and Suspensions  Mixture—a material composed of 2 or more substances that are physically mixed (but NOT chemically combined)  Solution—a type of mixture where the molecules are evenly distributed  Suspension—a mixture where the particles are NOT completely dissolved

Solutions  Solutions have two parts: Solute—substance that is dissolved Solute—substance that is dissolved Solvent—the liquid in which the solute dissolves Solvent—the liquid in which the solute dissolves

pH Scale  The pH scale ranges from 0 to 14 and shows the concentration of H + ions.  The lower the pH, the more acidic the solution. (Acid = below 7)  The higher the pH, the more basic (alkaline) the solution. (Base = above 7)

Acids and Bases  Pure water has a pH of 7, which is neutral.  Acids are compounds with more H + ions than pure water. pH of Strong Acid = pH of Strong Acid = pH of Weak Acid = 4 – 6.9 pH of Weak Acid = 4 – 6.9  Bases are compounds with more OH - ions than pure water. pH of Strong Base = pH of Strong Base = pH of Weak Base = pH of Weak Base =