Ch. 2

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Ch. 2

• CHEMISTRY

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Matter has mass and takes up spaceMass
quantity of matter an object has.
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Elements pure substances that can not be broken
down. Each has its own chemical symbol. We find
elements arranged on the periodic table of
elements. 90 of all living things contain
the elements O, C, H, and N. Atoms Simplest
particle of an element.
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• Molecules simplest part of a substance
• Atoms
• Nucleus core of atom
• Proton positive electrical charge
• Neutron no charge
• Atomic Number number of protons

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• Electrons negative charge particles that orbit
  in shells around nucleus.
• Electrons are the same number as protons.

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• Compound 2 or more elements combined together.
• Ex Water H2O
• The subscript shows the number of atoms of each
  element. (2 2 hydrogens)
• Chemical Reaction atoms become rearrange, and
  new bonds form. A new substance is made.

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Bonds energy that holds compounds together

• Covalent bonds are 2 atoms that share 1 or more
  pairs of electrons. Usually between non metals
• Ex water
• Ionic formed by electrical attraction between .
  No actual sharing takes place. Usually between
  metals.
• Ex Salt NaCl

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Energy

• Energy is the ability to do work or cause change.
• State of matter are solid, liquid and gas.
• Reactant is involved in the chemical reaction.
• Product is the product that is formed by the
  reaction.

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• Energy for our bodies are provided mainly by
  sugars from the foods we eat. These sugars are
  broken down by chemical reactions that produce
  the energy.

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• Exergonic energy is the release of energy.
• Endergonic energy absorption of the energy.
• Catalysts reduce the energy needed for the
  reaction to occur.
• Enzymes catalysts that are used in living things

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• There is a constant flow of energy in all living
  things. Most reactions deal with movement of
  electrons.

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• Many reactions involve a transfer of electrons
  called Oxidation-Reduction, or Redox reactions.
• Oxidation is the loss of electrons
• Reduction is the gain of electrons

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• Most systems in anything living involve water, or
  some combination of substances dissolved in
  water.

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• Solutions 1 or more substances dissolved in
  another substance.
• Solute dissolved in solution. In smaller
  amount
• Solvent substance in which solute is dissolved
• Concentrated amount of solute in the solution
• Saturated no more solute can be dissolved.
• Aqueous solutions water is the solvent

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• Mixture 2 or more substances that have variable
  composition.
• Homogeneous the same through out.
• ex milk
• Heterogeneous different through out.
• Ex rocky road ice cream

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• Dissociation is the breaking apart of the water
  molecule into 2 ions of opposite charge.
• Acids have a greater number of hydronium (H)
  ions. 0-7 on pH scale
• Base (alkali) have a greater number of hydroxide
  ions (OH) 7-14 on pH scale
• pH is the way of measuring H or OH ions. It
  stands for Potential Hydrogen
• Buffers are substances use to neutralize

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• Physical properties and changes describe what is
  observed by the senses and the changes in
  appearance only. The substance remains the same.
• Ex color, shape, mass, density
• Chemical Properties and Changes describe how a
  substance reacts with other substances and the
  new substances that are formed.
• Ex. Rust, baking