Section 2.1 What three subatomic particles make up atoms? How are all of the isotopes of an element similar? What are the two main types of chemical bonds?

2.1 Vocabulary atom ionic bond nucleus ion electron covalent bond element molecule isotope van der Waals forces compound

Chapter 2 The Chemistry of Life Atom – the building blocks of matter (100 million atoms side by side = 1 cm in length) Subatomic particles in the atom: 1. Protons Inside the ________________ 2. Neutrons 3. Electrons

Protons – positive charge (atomic #) Neutrons – neutral (no charge) Electron – negative charge Protons and neutrons about the same mass Electron is very small (1/1840 mass of proton) Electrons in constant motion around the nucleus

Elements in the human body # Protons = # electrons Overall charge of atom is _________ Proton # also called the _____________ ________________.

Elements Pure substance Made of one type of atom More than 100, but only about 25 in living organisms

The Periodic Table of Elements Interactive

Isotopes Atoms of the same element that have a different number of neutrons Identified by their mass number example: C-12 C-13 C-14 All isotopes of an element have the same chemical properties b/c same number of electrons

Radioactive Isotopes Nuclei are unstable and break down at a constant rate over time Important scientific/practical uses Geologists determine age of rocks and fossils Treat cancer Kill bacteria that cause food to spoil Labels (tracers) to follow movements of substances in organisms

Chemical Compounds Substance formed by the chemical combination of 2 or more elements Combine in definite proportions Use chemical formulas to identify them (H 2 O, NaCl) Physical and chemical properties of a compound are different from the elements making it up

Chemical Bonds Bonding involves the electrons in the atoms Ionic Bond forms when electrons are transferred from one atom to another Cation-an atom that loses electrons, positive charge Anion-an atom that gains electrons, negative charge

Ionic Bond NaCl

Covalent Bonds Electrons are shared between atoms Single bond ______ electrons shared Double bond ______ electrons shared Triple bond _______ electrons shared Molecule- smallest unit of most compounds -formed when atoms bond covalently

Covalent Bond H 2 O

van der Waals forces Intermolecular forces of attraction Molecules get close together and attraction develops between oppositely charged regions of nearby molecules Gecko, pg. 39

Gecko Gecko’s foot covered by half a million tiny setae Comes in contact with a large area of the wall at molecular level

The Water Molecule Polar

Cohesion Attraction between molecules of the same substance

Adhesion Attraction between molecules of different substances Capillary action

Solutions & Suspensions Mixtures Solutions Solute Solvent

Suspension Mixture of water and non- dissolved material

Acids, Bases, pH Water  Hydrogen ion + Hydroxide ion pH Scale shows concentration of Hydrogen ions in solution Acidic solutions Basic solutions

Buffers Control pH to maintain Homeostasis

Carbon Compounds (2.3) Organic Chemistry Carbon has 4 valence electrons

Macromolecules “giant molecules” Formed by polymerization Small units (Monomers) join together to form polymers

Four groups of Organic Cmpds. Found in Living things 1. Carbohydrates - made up of C, H, O 1:2:1 Main source of energy for living things Structural in plants and some animals Glucose broken down, supplies energy Extra sugar stored as complex CHO  STARCH starch = polymer sugar molecules = monomers

Monosaccharides -single sugar molecule -glucose, galactose, fructose Polysaccharides -formed from monosacc. -extra sugar stored in glycogen

Carbohydrates Glucose Starch

Lipids Insoluble in water Made mostly from C and H Fats, oils, waxes Used to store energy Part of biological membranes and waterproof coverings Steroids (chemical messengers, ex. cholesterol) are lipids

Structure of Lipids Glycerol + fatty acids (fig.2-14) Saturated-each C in the F.A. is joined to a C by single bond (F.A. contains the max. no. H atoms)

Unsaturated-at least one C-C double bond in the F.A. Polyunsaturated-F.A. contains more than one double bond Unsaturated-liquid at room temp. Cooking oils = polyunsaturated

Nucleic Acids Macromolecules made up of H, O, N, C, P Polymers assembled from nucleotides (monomers) Nucleotides made of 3 parts:

Nucleic acids Store and transmit genetic information Two kinds of N.A. 1. RNA (ribose) 2. DNA (deoxyribose)

The structure of a nucleic acid Nucleotide Adenine Thymine Cytosine Guanine Nucleotides

Proteins Macromolecules, contain C, H, O, N Made up of amino acids -amino group -carboxyl group -More than 20 different A.A. in nature -the side chain called the R-group is different

Functions of Proteins Control rate of reactions Regulate cell processes Used to form bones, muscles Transport materials into or out of cells Help fight disease Up to 4 levels of organization