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