Matter and its Changes

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Matter and its Changes
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Atoms

• Matter is made up of atoms
• Matter is anything that takes up space and has
  mass
• Atoms are the building blocks of life

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• Forms of matter that contain only one type of
  atom are called elements
• Atoms combine to form many different types of
  matter

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Structure of an Atom
Electron (electron cloud)
Proton
Mass Number Protons Neutrons
Atomic Number Number of protons
Neutron
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Isotopes

• When the number of protons in an atom changes it
  becomes a different element
• Atom is electrically neutral when there are more
  neutrons than protons
• Atoms of the same element that have a different
  number of neutrons are called isotopes
• Ex. C12 6p 6n C14 6p 8n

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Ions

• Electrically charged atoms are called Ions
• The number of protons is not equal to the number
  of electrons
• Ions are attracted to each other when they have
  opposite charges
• Ex. Na Cl- NaCl salt
• Ex. Na F- Sodium Fluoride for
  toothpaste

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Combinations of Atoms
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• Atoms combine by sharing their outermost
  electrons in their electron clouds
• When two atoms are combined a molecule is formed

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Bonds

• Ionic Bond Positive and Negative ions combine
  and electrons are transferred
• Ex. NaCl
• Covalent Bond Electrons are shared
• Ex. H2O

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Combinations of Atoms
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How Atoms Combine

• When at least two atoms are combined a molecule
  is formed
• There are two ways in which atoms combine to form
  molecules and compounds

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Ionic Bonding

• Positive and Negative ions combine and electrons
  are transferred
• Example Na and Cl- NaCl

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Covalent Bonding

• In covalent bonding electrons are shared
• Example 2H O H2O

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Compound

• A type of matter that has properties different
  from the properties of each of the elements in it
• Example Na (metal) Cl (gas) NaCl (solid
  salt)
• Example 2H (gas) O (gas) H2O (liquid water)

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Mixture

• Many different substances that when mixed
  together, each substance retains its own
  properties
• Examples sand, air and salad

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Solution

• When one substance of a mixture is dissolved in
  another substance it is a solution
• Examples tea w/ sugar, salt water

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Chemical/Physical Properties

• Chemical properties describe how one substance
  changes when it reacts with another
• Examples iron and oxygen rust
• Physical Properties can be observed or measured
  without changing the substance
• Examples color, shape, size, density and texture

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Density
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What is density?

• The measure of the mass of an object divided by
  its volume.

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• 4. Liquid to a solid freezing point
• 5. Solid to a liquid boiling point
• 6. Only substance that occurs naturally as a
  solid, liquid, and gas Water

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Matter can change by

• Increasing or decreasing the temperature
• Ex freezing water turns it to a solid (ice)
• 2. Increasing or decreasing pressure
• Ex Pressure to ice cube changes it to liquid

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Energy from Atoms

• What is nuclear energy?
• Alternate energy source produced from atomic
  reactions
• 2. How fission produces nuclear energy
• - Splitting the nucleus of atoms in heavy elements

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• 3. Most commonly used fuel in nuclear power
  plants
• - Uranium 235
• Where is it found?
• - Sandstones in the Rocky Mountains

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• 4. Major source of nuclear waste
• - Radioactive material
• Most common method of storing nuclear waste
• Power plants
• Can remain active for 10,000 years

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Two advantages to storing nuclear waste at Yucca
Mountain

• Remote area (deserted)
• Water table is far below storage facility

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Two disadvantages to storing nuclear waste at
Yucca Mountain

1. Earthquakes could destroy storage facility
2. Large amount of nuclear waste in one area