Chemistry of Life All living and non-living things are made up of elements Elements are substances that cannot be broken into anything more simple Elements are made of atoms Atoms are the smallest particle of an element that still have the characteristics of that element

Chemistry of Life Atoms are made of three subatomic particles Protons Positive charge p+ Electrons Negative charge e- Neutrons No charge n0

Chemistry of Life Protons and Neutrons are located in the nucleus of an atom What charge does the nucleus have? Electrons are located in the regions that surround the nucleus (electron cloud) The number of protons always equals the number of electrons so atoms have no overall charge

The Chemistry of Life Reading the periodic table Chemical symbol: 1 or 2 letters that represent that element Atomic Number: Indicates the number of protons and electrons in a normal atom that element Atomic Weight: number with a decimal in most squares, total mass of all the subatomic particles in one atom of that element

Chemistry of Life

Compounds and Bonds Compound Substance that is composed of atoms of two or more different elements that are chemically combined. Atoms combine to become more stable Atoms are most stable when their outermost energy level is full with 8 electrons Examples: H20, CO2, NaCl

Compounds and Bonds Elements bond together to form compounds Covalent Bonds Atoms share electrons to become more stable Example: water Ionic Bonds When atoms combine because they gained or lost an electron to become more stable Example: sodium chloride (salt)

Chemical Reactions Bonds between atoms are formed or broken causing new substances to be produced Energy changes accompany chemical changes Observable energy changes Heat used or given off Light Metabolism is all of the chemical reactions within an organism

Writing Chemical Formulas 2C12H22O11 The subscript number in a formula indicate the number of atoms of each element in molecule of the substance. The number in front of the chemical formula tells us the number of molecules of each substance.

Compounds vs Mixtures Compounds Mixtures Two or more elements combined in a fixed ratio Examples CO2 H2O CH4 C6H12O6 Mixtures Combination of substances in any proportion NOT chemically bound Each substance keeps its own properties Examples Trail Mix Kool Aid Salt and Sand mixture

Solutions A mixture of two or more substances where both are evenly distributed Examples Salt water Sweet tea Water vapor in the air

Acids and Bases pH is a measure of how acidic or basic a solution is A scale of 0-14 is used to measure pH Acids form H+ ions and have a pH below 7 Bases form OH- ions and have a pH above 7 Neutral solutions have a pH of 7