Composition of Matter All matter is composed of Atoms

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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

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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 cased
Name
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
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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

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Bohrs Model

• 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-
6P 6N
e-
e-
e-
e-
Carbon atom
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Must remember that

• Bohrs 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

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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

??
?
?
?
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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
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Types of Bonds

• Covalent Bonds
• Atoms may share electrons to fill valence shell
• ex. H2O

• Ionic Bonds
• Atoms may gain or lose electrons to fill its
  valence shell
• This creates an imbalance of and creating a
  charged atom or ION
• Opposites attract
• Ex NaCl-

• Hydrogen Bonds
• Occur between H (only have 1 electron)
• weak bond
• Ex surface tension between H2O molecules

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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

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Molecules and Compounds

• Molecule 2 definitions
• 2 or more atoms of the same element
  
• joined together O2 H2 O3
• Smallest unit of a compound that has the
  properties of that compound
• Compound
• 2 or more different elements chemically
• combined
• H2O CO2 C6H12O6

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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

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Lipids are insoluble in water

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

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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 (lt 7)
• More OH- basic (alkaline) (gt7)
• Equal amounts H OH- Neutral (pH7)

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States of MatterMatter on Earth can be found in
three states

• Solids molecules are barely moving
  
  (ice cube)
• Little energy
• Definite volume
• Definite Shape

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States of Matter

• Liquids - molecules moving fairly freely
  (water)
• More energy
• Definite volume
• No definite shape

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States of Matter

• Gases molecules are moving rapidly (steam)
• Lots of energy
• No definite volume
• No definite shape

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Physical Change

• How do you know you saw a PHYSICAL CHANGE?

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Change inState, shape or size
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Change in STATE
Liquid
Solid
Gas
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Change in SIZE
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Change in SHAPE
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Chemical Change

• How can you tell there was a CHEMICAL REACTION!?
  Something NEW is formed

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New solid formed
Precipitate
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Unexpected color change
Clear Clear ?
PURPLE
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Temperature change
Increase (endothermic) or Decrease (exothermic)
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New gasformed
Bubbles
Odor/smell
Steam
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Quiz Identify as Chemical or Physical Change
Physical
Slicing bread
Rust on nail
Chemical
Chemical
Baking bread
Physical
Melting Ice cream