Composition of MatterAll matter is composed of Atoms

Protons Found in the nucleus

of atom positive (+) charge Mass Value 1

Neutrons found in nucleus of

atom neutral (no) charge Mass value 1

Electrons found in clouds

orbiting around nucleus

negative (-) charge Mass value 0

Periodic Table of ElementsEach element is made up of same atoms

1

H

Hydrogen

1.0079

Atomic Number = Number of Protons (# P = # of electrons)

Symbol – 1st letter always CAPITAL 2nd letter always lower casedName

Atomic Mass = Number of Protons + Number of Neutrons

Number of Neutrons = Atomic Mass - Atomic Number

Number of electrons must equal the number protons

or the atom will be charged (+ or -) = Ion

Atomic Models

Most often represented as series of circles

Center circle represents

the nucleus - containing the

protons (P+)and neutrons (N)

Outer circles represent

the electron clouds where

electrons (e-) orbit

Bohr’s Model

6P

6N

e-

Each valence (orbit) has a specific number of electrons it can hold

1st holds up to 2 e- 2nd holds up to 8 e- 3rd holds up to 8 e- 4th holds up to 18 e-

e-

e- e-

e-

e-

Carbon atom

Must remember that:

Bohr’s Models are simple 2D models Atoms are actually 3D

Electrons actually move around nucleus in an electron cloud not a linear orbit

Atoms are active – drawings are stationary

Lewis Dot Model

Uses dots to show Valance electrons – outermost orbit

Valence Electrons are the ones that make the atom interactive

Arranged in pairs on 4 sides of symbol – Shows “empty seats”

N

Why do Atoms React?

They want to fill their “empty seats” on valence orbit Nitrogen has 3 “empty seats”

Can add or lose electrons IONic bond Can share electrons Covalent

N

X

X

X

Types of Bonds

Ionic BondsAtoms may gain or lose electrons to fill its valence shellThis creates an imbalance of + and – creating a charged atom or IONOpposites attractEx Na+Cl-

Covalent BondsAtoms may share electrons to fill valence shell ex. H2O

Hydrogen BondsOccur between H (only have 1 electron)

weak bondEx surface tension between H2O molecules

Why is Carbon so Important?

• Carbon has 6 protons; therefore has 6 electrons

• This leaves 4 empty seats for Carbon to fill

• Carbon will bond with LOTS of things BUT likes to bind with other C atoms.

• This creates the rings and chains of all the organic compounds

Molecules and CompoundsMOLECULE – 2 definitions

1) 2 or more atoms of the same element

joined together O2; H2; O3

2) Smallest unit of a compound that has the properties of that compound

COMPOUND2 or more different elements chemically

combined

H2O; CO2; C6H12O6

Polarity of Water

Water (H2O) is made up of 2 H and 1 O sharing their electrons (covalent bond)

There is a higher concentration of electrons on the Oxygen end making it slightly negative and the Hydrogen end slightly positive

Lipids are insoluble in water

Because they are•Not polar•Have no ionic bondsTherefore, they are NOT attracted to water

pH The concentration of H+ in a

solution measures the acidity or basicity of the solution H2O will break apart creating hydrogen ions

(H+ ) and hydronium ions (OH-) More H+ = acid (< 7) More OH- = basic (alkaline) (>7) Equal amounts H+ & OH- = Neutral (pH7)

States of Matter:Matter on Earth can be found in three states:

SOLIDS – molecules are barely moving; (ice cube)

Little energy Definite volumeDefinite Shape

States of Matter

LIQUIDS - molecules moving fairly freely (water)

More energy Definite volume No definite shape

States of Matter

GASES – molecules are moving rapidly (steam)

Lots of energyNo definite volumeNo definite shape

Physical Change

How do you know you saw a PHYSICAL CHANGE?

Change in:State, shape or size…

Change in STATE

Solid

Gas

Liquid

Change in SIZE

Change in SHAPE

Chemical Change

How can you tell there was a CHEMICAL REACTION!? Something

NEW is formed…

New solid formed

Precipitate

Unexpected color change

Clear + Clear PURPLE

Temperature change

Increase (endothermic) or

Decrease (exothermic)

New gasformed

Bubbles

Odor/smell

Steam

Quiz – Identify as Chemical or Physical Change

Slicing bread Physical

Rust on nail

Baking bread

Melting Ice cream

Chemical

Chemical

Physical