The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS: Dalton

2. Elements-substances that consist of just one type of atom; they cannot be broken down to other substances 1. Atom-the basic unit of all matter; the smallest unit of matter that retains the properties of an element 3. Molecule-substance containing 2 or more atoms 4. Compound-substance containing 2 or more elements

Is brass an element? What about: Oxygen O 2 Water H 2 0 Helium He Is brass a molecule? Is brass a compound?

The structure of the atom ELECTRON negative, orbits outside the nucleus in the ELECTRON CLOUD PROTON positive, also in nucleus NEUTRON neutral, located in the NUCLEUS (center of atom)

+++++ positive and negative are opposites they cancel each other out net charge = zero

+++++ In an atom, protons ( ) are in the center and electrons ( ) are on the outside + only electrons ( ) can be added or taken away

This is an atom with 5 electrons and 5 protons The atom is neutral 5 (-) and 5 (+) = zero charge (neutral)

+++++

+++++ charge = ?

+++++ charge = -1 (negative one)

+++++

++++ charge = ?

(positive two )

WHEN REMOVING ELECTRONS THE RESULTING CHARGE IS POSITIVE

THE RESULTING CHARGE IS NEGATIVE WHEN ADDING ELECTRONS

An atom with positive or negative charge is called an drum roll ION

Hydrogen atoms are very reactive…. Helium is not. Which do you think the Hindenburg was filled with? Atoms want 8 electrons in the outermost shell. If atoms have less than 8 then they react with other atoms to gain or lose electrons.

Atoms will react to get 8 electrons in the outer shell. This can cause the atoms to bond with each other. FK IONIC bond – bond formed when electrons are lost from one atom and gained by another.

FK

FK

FK

FK

FK

FK

FK + _

FK + _ The compound potassium fluoride consists of potassium (K + ) ions and fluoride (F - ) ions

FK + _ The ionic bond is the attraction between the positive K + ion and the negative F - ion

In covalent bonding, atoms still want 8 electrons in the outer shell But rather than losing or gaining electrons, atoms now share an electron pair

Cl Each chlorine atom wants to gain one electron to achieve get 8 Chlorine forms a covalent bond with itself

Cl

8

circle the electrons for each atom that completes their octets 8

Cl circle the electrons for each atom that completes their octets Each atom has 8 electrons because they share the electrons in the middle

Cl circle the electrons for each atom that completes their octets It is called a SINGLE BOND

Cl circle the electrons for each atom that completes their octets Single bonds are shown with a dash

O2O2 Oxygen

How will two oxygen atoms bond? OO

OO Each atom has two unpaired electrons

OO

OO

OO

OO

OO

OO

Both oxygen atoms want to gain two electrons. OO

OO

OO

OO

OO

O O Both electron pairs are shared.

8 O O

8 O O

two sets of shared electrons, O O making a double bond

O O = The double bond is shown as two dashes. O O

O O = This is the oxygen molecule, O 2 this is so cool! !

Covalent bonding allows for an amazingly large variety of compounds such as

small compounds like water and carbon dioxide,

and alcohol (ethanol),

and larger compounds such as aspirin, (21 atoms)

and all of the 40,000 different proteins you have in your body, including

insulin, with about 900 atoms,

and hemoglobin, with about 11,000 atoms!

Biomolecules Molecular basis of life

Polymers “mer” means unit “mono” means one Monomer-one unit “poly” means many Polymer-many units Polymers are made of many monomers

Biomolecules Four majors types of Biomolecules Carbohydrates Proteins Nucleic Acids Lipids

Carbohydrates Monomer- simple sugar like glucose Stores energy and provides structure Blank

Proteins Monomer-amino acid Provide structure Enzymes-speed up chemical reactions

Monomer-Nucleotide Stores and transmits genetic information Two types Deoxyribonucleic acid – DNA Ribonucleic acid - RNA Nucleic Acids

Lipids Used to store energy One gram of fat contains over twice the energy of one gram of carbohydrate Important categories Fats, Oils, Waxes Steroids Phospholipids Structure Glycerol molecule + 3 fatty acids

Water is Polar The oxygen end (pole) of water has a negative charge The hydrogen end (pole) has a positive charge

Hydrogen bonding The hydrogens of one water molecule are attracted to the oxygen from other water molecules. This attractive force is called hydrogen bonding

Hydrogen bonding IceLiquid

Cohesion and Adhesion Hydrogen bonds give water its cohesive and adhesive properties. Cohesion-water is attracted to other water Adhesion-water attracted to other materials

Surface tension Cohesion of water molecules at the surface of a body of water

Capillary Action Water climbs up capillaries (like straws or plant stems) The water molecules are attracted to the capillary molecules. When one water molecule moves closer to the capillary molecules the other water molecules (which are cohesively attracted to that water molecule) also move up into the capillary. Capillary action is limited by gravity and the size of the capillary. The thinner the capillary the higher up capillary action will pull the water

High Specific Heat Water does not change temperature easily This is why coastal areas have a more constant temperature. This is also why life forms have a more constant temperature.

Solutions Solutions are mixtures where the solute is evenly distributed in the solvent (completely dissolved) Water is a very good solvent

Water and Life Water is essential for life. Most animals and plants contain more than 60% water by volume. Without water life would probably never have developed on our planet.