The Basics of ChemistryChemistry in Biology

1. What is Matter? (Reading 2.1)Matter is everything that takes up space and

has massEvery matter is made up of atoms of one of

92 natural elementsLiving organisms are composed of matter

2. Atoms and Elements of Life (2.1 and 2.3)Atom: The basic unit of every matter.Element: a substance that is made up of only

one type of atom.Living organisms are composed of about 25

elements. The most important elements make up about

96% of all living organisms. These elements are carbon (C), hydrogen (H), oxygen (O) and nitrogen (N)

Other important elements are calcium (Ca), phosphorous (P), sodium (Na), potassium (K), chlorine (Cl) and magnesium (Mg)

3. Subatomic Particles (2.4, 2.5)Atoms are dividable to 3 main subatomic

particles:Protons are positive and located in the nucleus

of the atomNeutrons are neutral and located in the

nucleusElectrons are negative and found on orbitals

around the nucleus

If two atoms have different numbers of protons they are different elements – atomic number – is the number that is assigned to every element and is equal to its number of protons

If two atoms have different numbers of neutrons but the same number of protons, these atoms are isotopes.

Many elements have radioactive isotopes – these are isotopes that have an unstable nucleus that decays and releases energy spontaneously (radioactive radiation)

Radioactive isotopes are frequently used in biology for:Basic research (radioactive tracers, dating

fossils)Medical diagnosis (radioactive tracers, medical

imaging, radiation treatment)Food industry (sterilizing and preserving food)

Radioactive isotopes are also dangerous because they can damage DNA molecules and in high doses can cause serious burns as well.

4. Chemical Bonds (2.3,2.6, 2.7)Atoms can bind with each other to form more

complex forms of matter called compounds.There are two basic types of bonds:

Covalent bond – electrons are shared between atoms

Ionic bond – electrons are lost or gained by atoms and the oppositely charged ions are held together by electrostatic attraction.

5. Polarity and Hydrogen Bonds (2.9, 2.10)Some molecules in covalent bonds share the

electrons equally or the molecule is symmetrical – nonpolar molecules (Ex. Oil)

Some molecules have an uneven electron sharing. One atom attracts the electrons more in the bond than the other – polar molecules (Ex. Water)

Some polar molecules form strong attractions between each other. If one molecule has oxygen, nitrogen or fluorine while the other molecule has hydrogen the two molecules form HYDROGEN BONDS with each other.

http://www.northland.cc.mn.us/biology/biology1111/animations/hydrogenbonds.html

6. Chemical Reactions (2.17)When chemical bonds break and new ones are

formed chemical reactions take place. Chemical reactions are represented by chemical

equationsWhen you write chemical equations, the reactants

are always written on the left side of the equation and the products on the right side of the equation. There is a = or an between the two sides of the equation.

Chemical equations must always be balanced.A chemical reaction:

http://www.youtube.com/watch?v=MUensqImzXM

7. The Characteristics of Water(2.11 – 2.14)See the given review tablehttp://www.youtube.com/watch?v=KSLUwmJOo_M

8. Acids and BasesAcids – substances that release hydrogen

ions into water Some important characteristics of acids: sour,

pH below 7, caustic.Bases – substances that release OH- ions into

water.Some important characteristics of bases:

slippery, bitter, pH above 7.Indicators – Substances that change their

color when placed in acids or bases (ex. phenolphthalein, litmus, tea, cabbage juice, methyl orange)

Buffers – substances that resist changes in the pH and keep solutions on a fairly constant pH even if acids or bases are added to them.