Chapter 2 Chemistry of Life 2.1 Composition of Matter 2.2 Energy 2.3 Water and Solutions

Composition of Matter Chapter 2 Composition of Matter Matter: Anything that occupies space and has mass. Mass: Amount of matter an object has. Elements: Made of atoms & can not be broken down into simpler substances.

6 Most common elements in organic molecules Carbon Hydrogen Nitrogen Oxygen Phosphorus Sulfur

Building blocks of matter Made of subatomic particles Atomic Structure Atom Building blocks of matter Made of subatomic particles Proton (p+) Neutron (n°) Electron (e-)

Atomic Structure Particle Charge Location Mass Proton (+) Nucleus 1 amu Neutron None Electron (-) Orbitals 1/1837 amu

The number of protons determines an element Comparing Atoms The number of protons determines an element Atomic number = # of protons 47 Ag 107.87 Atomic Mass # = # p + # n

Isotopes Isotopes are atoms of the same element that have different numbers of neutrons. These are all isotopes of hydrogen.

Neutron number changes = Isotope Electron number changes = Ion Ions Neutron number changes = Isotope Electron number changes = Ion Ion (charged atoms) Compare the number of protons & electrons Positive charge: More protons than electrons Negative charge: More electrons than protons

Ionic Bonding Transfer of electrons Bond between metal an non-metal Composition of Matter Chapter 2 Ionic Bonding Transfer of electrons Bond between metal an non-metal

Covalent Bonds Electrons are shared Composition of Matter Chapter 2 Covalent Bonds Electrons are shared Bond between non-metal and non-metal. Each atom fills up its outermost energy level

2.2 Energy Ability to do work Conversion of energy from one form to another. Chemical Energy Mechanical Energy Thermal Energy

Chapter 2 Energy and Matter States of Matter Addition of energy to a substance can cause its state to change from a solid to a liquid and from a liquid to a gas.

Energy & Chemical Reactions Chem. Rx: One or more substances change to produce one or more different substances. Always involves change in energy Making or breaking chem. bonds

Chem. Rx. in capillaries CO2 + H2O H2CO3 Reactants Products

2 Types of Chem. Rx. Endothermic (Energy absorbed) Exothermic (Energy released)

Chapter 2 Exothermic Cellular respiration Endothermic Photosynthesis

Activation energy: Energy needed to start a chemical reaction. Reaction rate: How quickly the reactants turn into products. Reaction rate depends on: Temp Surface area Concentration Catalysts

Catalysts: Reduces the amt. of activation energy that is needed for a reaction to take place. Enzymes: Proteins that act as catalysts in living cells. Factors affecting enzyme activity Heat, Acidity, Concentration

2.3 Water and Solutions All Chem. Rx. take place in the cell in solution. Water molecule: Polar Allows it to dissolve polar substances (like sugars, ionic cmpds) “Like dissolves Like” Water is considered to be a polar molecule due to an uneven distribution of charge. The electrons in a water molecule are shared unevenly between hydrogen and oxygen.

Hydrogen Bonding Force of attraction between H (+) charge & (-) charge on another atom or molecule.

Chapter 2 Hydrogen Bonding Water and Solutions Chapter 2 Hydrogen Bonding A hydrogen bond is the force of attraction between a hydrogen molecule with a partial positive charge and another atom or molecule with a partial or full negative charge.

Acids & Bases Water ionizes into: Neutral: (H3O+) = (OH-) Hydronium ions (H3O+) Hydroxide ions (OH-) Neutral: (H3O+) = (OH-) Acids: Contains more (H3O+) ions Bases: Contains more (OH-) ions

Water and Solutions Chapter 2 The pH Scale A scale for comparing the relative concentrations of hydronium ions and hydroxide ions in a solution. Ranges from 0 to 14.