The Chemistry of Life Chapter 2

The Chemistry of Life Before we can talk about biology, we need to discuss Chemistry The atom is the most basic unit of matter All atoms are made up of three parts: Protons (nucleus)—Positive Electrons—Negative Neutrons (nucleus)—Neutral

Atoms Because protons are positive, the nucleus is positive; BUT the electrons (negative) cancel out the charge Each element’s atomic number is the same as the number of protons Each element’s atomic mass is the total number of protons and neutrons

Practice What is the atomic mass of Carbon if Carbon has 6 protons and 6 neutrons? What is the atomic number of Oxygen if Oxygen has 8 electrons? What is the atomic mass and number of Magnesium if Magnesium has 12 electrons and 12 neutrons?

Ions & Isotopes Some atoms can lose or gain electrons, making the atom positively or negatively charged. These atoms are called ions Some atoms of the same element have different numbers of neutrons, giving them different weights. These atoms are called isotopes

Chemical Compounds A chemical compound is a substance made up of two or more elements H2O CO2 NaCl The chemical formula tells what and how much is in the compound

Chemical Bonds 2 kinds of chemical bonds: Ionic Bonds Formed between ions (atoms that have lost or gained electrons) One atom gives electrons to the other Covalent Bonds Electrons are shared between atoms

Chemical Bond EXamples Covalent Bond Ionic Bond

Properties of Water Using the Bio Book, define the following terms: Cohesion Adhesion Mixture Solution Solute Solvent Suspension pH Scale Acid Base Buffer

Properties of Water Cohesion—when water molecules stick to each other Adhesion—when water molecules stick to a surface Surface Tension—force in the surface of a liquid that causes the layer to behave like an elastic sheet Solvent—liquid that dissolves other substances