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

• Covalent Bonds– Atoms share

electrons to become more stable

– Example: water

Elements bond together to form compounds

• 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– 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