Chemistry – study of matter and the changes it undergoes.

Chemistry – study of matter and the changes it undergoes

Only 1 kind of atom

2 or more different kinds of atoms

• Element is a pure substance made up of only one kind of atom.

• Families (groups) – vertical columns– Elements in a family have similar properties

• Periods – rows, left to right add another proton and electron – filling up outer energy (valence) level

Elements are Made of Atoms• The single smallest unit of an element that

retains all of the chemical and physical properties of its parent element is called an atom.

Atoms are made up of smaller, subatomic pieces called protons, neutrons and electrons

Helium

Atoms are composed of three types of subatomic particles

1.Electrons: have a negative charge and are the smallest part of an atom

2.Protons: have a positive charge and mass of 1amu

3.Neutrons: have no charge 4.1 neutron = 1 amuProtons and neutrons clump to make the nucleus

The electrons surround the nucleus and form the much larger electron cloud.

Atomic Number• Atomic number

defined as the number of protons

• Because atoms are neutral: # electrons = # protons

• Atoms of the same element always have the same atomic number

2 3

11

Chemical Bonds

• Atoms are not stable unless their valence (outermost) energy level is filled.

• By forming bonds with other atoms, valence levels are filled.

Barium

Two types of bonds

• Atoms may fill their valence levels one of two ways: – share electrons with other atoms to form a covalent

bond

or – Atoms can gain or lose electrons to create an ionic

bond

Ionic Bonds (Salts)

• Formed when electrons are transferred between atoms – one loses and the other gains

• Atom that has gained or lost an electron is now charged and called an ion

• Atom that loses electrons becomes + and the one that gains is -

Covalent Bonds

Electrons are shared: single pair shared = single covalent bond, 2 pairs shared = double covalent bond

Chemical Formulas

• Tell kinds and numbers of atoms in one molecule (or smallest unit) of a substance

• Subscripts tell the number of atoms of the element to the upper left (of the subscript).

• Eg. H2O

– Tells us there are 2 atoms of H and 1 of O in one molecule of water (if no subscript, then it is understood to be 1)

• CO2

– 1 carbon dioxide molecule has 1 carbon atom bonded to 2 oxygen atoms.

Chemical Equations

• Represent chemical reactions, which obey the law of conservation of matter – the kinds and numbers of atoms that enter into the reaction also come out!

• Coefficients tell how many of the molecules they precede are involved.

• Eg. 2Mg + O2 2MgO

– Read as magnesium plus oxygen yields magnesium oxide

Substances to the left of the arrow are reactants, and substances to the right are products

In this reaction, 2 atoms of magnesium react with 2 atoms of oxygen to produce 2 molecules of

magnesium oxide.

• pH refers to the concentration of H+ or OH- ions

• Lower pH – higher concentration of H+ and the greater the acidity

• Higher pH – higher concentration of OH- and the greater the alkalinity (base)

• Organisms – and tissues within organisms have specific pH requirements.

Inorganic Molecules

• Simple Structure• H20, 02, NH3, CO2

Inorganic even though it contains carbon - exception

Biological MacromoleculesOrganic (contain carbon)

Molecule

(polymer)

Building

Blocks

(monomers)

Function Sources

Protein Amino acids Structure, enzymes, hormones

Eggs, fish, chicken, meat, nuts, legumes, dairy

Carbohydrates

polysaccharides (starch – cellulose)

Monosaccharides

Simple sugars

(glucose)

Energy Fruit, veggies, bread, potatoes,

pasta, grains

Lipids (fats and oils)

Fatty acids and

Glycerol (Not monomers)

Energy, structure, hormones

Vegetable oils (olive, safflower), animal fats (butter)

Nucleic acids

DNA & RNA

Nucleotides Carry genetic code and direct protein

synthesis

Cells

CARBOHYDRATES

• Sugars, Starches, Cellulose

• Contain C,H,O in a ratio of 1:2:1– Ratio of H:O is 2:1 just like H2O

– Eg. C6H12O6

• Energy & energy storage

sugarstarch

cellulose

Glucose

• A monosaccharide C6H12O6,

• major source of energy in the body.

Monosaccharide + monosaccharide disaccharide

Polymerization

• Smaller units (monomers) are bonded together to make larger units (polymers)

• A disaccharide such as maltose or sucrose is made from the dehydration synthesis (condensation reaction or removal of H2O) of 2 monosaccharides

• If more than 2 monosaccharides are bonded through dehydration, a polysaccharide (starch) is made. Cellulose is an example

PROTEINS

• Composed of monomers called amino acids

• Contain C, H, O, sulfur and nitrogen!

• Structure and chemicals that affect other body processes: enzymes, hormones

Peptide bondA dipeptide results

Amino Acids

There are 20 different types of amino acids found in the natural world.

LIPIDS

• Fats, oils and waxes• Contain C,H,O with a very high ratio of

carbon and hydrogen to oxygen.• Composed of fatty acids and glycerol• Uses:

– Cell membrane structure– Energy– Some Hormones– Insulation

Lipids Include all of the fats, oils and waxes.They have higher ratios of Carbon & Hydrogen than

oxygen.

Saturated vs Unsaturated Fatsunsaturated has double bonds

Nucleic Acids

DNA & RNA: carry genetic code

Made of repeating units called nucleotides:

Sugar + phosphate + N base

Contain P

nucleotide