BASIC CHEMISTRY Honors Biology

Recall: Levels of Organization

Biology Depends on Chemistry  In our biosphere, everything is made of atoms  Through the interaction of chemicals we can better understand our biosphere Give an example from what we have already done in Bio.

2 MAIN AREAS 1.NUCLEUS -center 2. ENERGY LEVELS -outer circle(s) THE ATOM

3 subatomic particles (small pieces of the atom) In the nucleus: 1. protons 2. neutrons In the energy levels: 3. electrons THE ATOM

A substance containing only one type of atom is: ELEMENT THE ELEMENT CARBON ATOM

All known elements are organized in the periodic table. The periodic table tells you information about each element PERIODIC TABLE

Information about elements Atomic Number- number of protons in the atom Chemical Symbol Atomic Mass- number of protons and neutrons Elements are not charged, therefore electrons always equal protons.

Find the following If the atomic number for H is 1: How many protons in H? If the atomic mass of H is 1: How many neutrons in H? How many electrons?

Find the following The atomic number for O is 8. How many protons in O? How many electrons in O? The atomic mass of O is 16. How many neutrons in O? Draw an Oxygen atom. Show the number of protons and neutrons in the nucleus and the electrons in the energy level.

Draw Nitrogen Draw Carbon  Nitrogen atomic number: 7 atomic mass: 14  Carbon atomic number 6 atomic mass: 12

Molecules  2 or more atoms held together by chemical bonds

A substance containing two different types of atoms is: COMPOUND All compounds are molecules but not all molecules are compounds THE COMPOUND CARBON ATOM OXYGEN ATOM What compound is this?

How many elements in each of the molecules below? How many atoms in each? CO 2 - carbon dioxide H 2 O - water C 6 H 12 O 6 - sugar (glucose) NaCl - salt O 2 - oxygen (usable)

Bonding IONIC BOND One atom gives an electron to another- this causes a charge in the atom Charged atoms are called ions.

Bonding Atoms share electrons in order to fill the last energy level of each “co-” means share Strong Bonds! COVALENT BOND

How many bonds can these make?  Hydrogen  Oxygen  Nitrogen  Carbon *How many electrons are needed to fill the outer energy level?

Bonds these make  Hydrogen - 1  Oxygen - 2  Nitrogen - 3  Carbon - 4

Chemical Bonds: Hydrogen  Weak bond formed from the unequal sharing of electrons  Slightly positive, slightly negative ends  Importance to biology: critical to water’s properties, holds DNA together

wh

Chemical Reactions  Synthesis  Make a compound  Ex: Photosynthesis  Decomposition  Break down a compound  Ex: Cellular Respiration  Both reactions important to biology: metabolism

 Chemical reactions are written like simple addition problems. H 2 O 3 H 2 O + O 2

Reactants (inputs): what goes in to the reaction Products (outputs): what comes out of the reaction

The body is factory of chemicals  Bonding takes place when chemicals react  This is called a chemical reaction