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Mr.Haight

Regular Biology

Elements and Atoms

A. Element-is a substance that cannot be broken down into simpler chemical substances

B. Over 112 elements currently on the table

C. Trace elements-Mg, Zn, and Fe

D. Atom-the smallest particle of an element that has the characteristics of that element

 

Elements in the Body

96 % of the mass in a human is:

a) Carbon

b) Hydrogen

c) Nitrogen

d) Oxygen

Structure of an Atom

Nucleus-center of an atom, contains protons and neutrons

Electron cloud-contains electrons that circle the nucleus

Energy levels: Holds electrons

1st 2 electrons

2nd 8 electrons

3rd 18 electrons

 

Compounds-a substance that is composed of atoms of two or more different elements

Water, Salt (NaCl) etc.

Covalent Bonds-atoms that share electrons (water)

Molecules are held together by covalent bonds

Ionic bond-Atoms that give up electrons to become stable when they combine (NaCl-salt)

pH scale

Based on powers of 10

Acids are below pH 7

Contain more H+ ions

Bases are above pH 7

Contain more (OH-) ions

Mixture-a combination of substances in which the individual components contain their own properties

Solution-A mixture in which one or more substances are evenly distributed

 

l    Bases are above pH 7

    Contain more (OH-) ions

l    Mixture-a combination of substances in which the individual components contain their own pSolution-A mixture in which one or more sSection 6-1