2.1 Nature of Matter

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2.1 Nature of Matter
Atom atomos unable to cut
- basic unit of matter which consists of 3
Subatomic particles.
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Proton

• Location in the nucleus (center)
• Mass 1 atomic mass unit (amu)
• Charge Positive (1)

3
Neutrons

• Location in the nucleus
• Mass 1 amu
• Charge no charge (neutral)

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Electrons

• Location outside of nucleus in orbitals
  (electron clouds, energy levels)
• Mass nearly 0 amu
• Charge Negative (-1)

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Electron Orbit (not really)

• Electrons in fact inhabit regions of space known
  as orbitals undefined paths.
• You can think of an orbital as being the region
  of space in which the electron lives (clouds).

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Element

• Def a pure substance that consists entirely of
  one type of atom.
• Ex - Gold

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Using the Periodic Table

• Detailed information about elements
• Strategically Arranged

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Periodic Table
Period elements in the same row, have similar
physical properties
Group elements in the same column, react in the
same ways
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Chemical Symbols
Atomic Number
Atomic Number the number of protons found in
the atom
6 C 12.011
1 2 letter chemical symbol
Atomic Mass the total number of neutrons and
protons in the atom. (Units amu)
Atomic Mass
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Try These
30 Zn 65.5
11 Na 23
How many protons?
11
How many protons?
30
How many neutrons?
12
How many neutrons?
35 - 36
Element Name?
Sodium
Element Name?
Zinc
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Isotopes

• Def atoms of an element that have different
  number of neutrons
• All isotopes have the same chemical properties.
  Why?

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Radioactive Isotopes

• Def isotopes that have unstable nuclei that
  become stable by releasing radiation
• Uses of Radioactive Isotopes
• Determine the age of rocks because the nuclei
  break down at a constant rate.
• Treat Cancer

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Compounds

• Def a substance formed by the chemical
  combination of two or more elements in definite
  proportions

H2O - Water
C6H12O6 - Glucose
NaCl - Salt
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Forming Chemical Compounds

• Ionic Bonds a bond formed when electrons are
  transferred from one atom to another.
• Ions atoms of the same element that have lost or
  gained an electron.
• 2-8-8(18) Rule Elements want to fill their
  outer shell by gaining or losing electrons.

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Valence Electrons

• Valence Electrons Electrons in the outermost
  shell of an atom.

Ionic Bonding
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Covalent Bonds

• Def A chemical bond that forms when electrons
  are shared between atoms.

Think about Hydrogen
Molecule the smallest unit of most compounds.
Animation
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Covalent Bonds
Why does Carbon usually form covalent bonds,
instead of ionic bonds?
Answer Outer shell is half full.
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Van der Waals Forces

• Sometimes in covalent bonds the sharing of
  electrons is not always equal.
• Slight attraction between slightly charged
  regions of a nearby molecules.
• A combination of ionic and covalent bonds

TED - Gecko Talk
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Basic observations about water

1. Use your pipette to make droplets of water on
   your desk. Write down any observations you made.
   
2. What happens if you make one drop very near to
   another one?
3. Use the penny I gave you as a surface to drop
   water on. See how many drops of water can be
   held on the surface of the penny before it
   spills.
4. Lastly, look at the inside of the pipette after
   youve squeezed all the water out. What do you
   notice?