Biology – the study of life Before we begin to study biology, we 1 st need to understand what life is made of! Remember that the basic unit of life is the cell. So, what are cells made of? Cells are made up of MOLECULES & ATOMS.

Introduction to Biochemistry

Matter Anything that has mass & takes up space NOT ENERGY

The 3 States of Matter Solid: molecules are very closely packed; definite shape & volume Liquid: molecules have more energy & are further apart; indefinite shape, but has a definite volume Gas: most energy among molecules; take the shape of container & fills space available; indefinite shape & volume

When energy is added or lost, the matter goes through changes.

Physical Changes Changes in substances that involve changing states or simply cutting the substance in half A substance is said to undergo a physical change if it simply changes from one state of matter to another.

Chemical Changes Changes that break chemical bonds & change the substance into something different When you cook an egg, the proteins change shape, which changes the texture & appearance of the egg. This is a penny being dissolved in nitric acid.

Baking a cake? A.Chemical Change B.Physical Change

Cutting down a tree? A.Chemical Change B.Physical Change

Boiling water? A.Chemical Change B.Physical Change

Remember! Matter is anything that has mass & takes up space. So what is matter made of?

Atoms Basic unit of matter Composed of: – Protons: positive (+) charge – Electrons: negative (-) charge – Neutrons: neutral, no charge

Protons & Neutrons Located in the nucleus Have a mass of 1 amu (atomic mass unit) What is the mass of the protons & neutrons in this atom?

Electrons Located around the nucleus in electron clouds (not actually rings!) Have a negligible mass, because they are hundreds of times smaller than protons & neutrons

So, how small are atoms?

Elements Pure substances made up of one type of atom All atoms of that element look the same, with the same number of protons, neutrons (average), & electrons. The number of protons indicates the type of atom!

Reading the Period Table of Elements Letters: symbol for the element, representation Atomic Number: number of protons Atomic Mass (weight): mass of the nucleus (# protons + # neutrons)

How many electrons are there? The number of protons is the same as the number of electrons. # protons = # electrons This gives the element a neutral charge!

How many electrons are in Cobalt? A.58 B.59 C.27 D.31 27! The atomic number is equal to the number of protons, which is the same as the number of electrons.

Atom Models Protons & neutrons are drawn inside of the nucleus. Electrons are drawn around the nucleus in energy levels (rings). Click photo to play video

Atomic Number Atomic Mass

How many neutrons are in Cobalt? A.27 B.59 C.25 D.32 32! Atomic mass = # protons + # neutrons. So, 59 – 27 = 32.

What element is this? A.Helium B.Potassium C.Nitrogen D.Carbon Carbon! There are 6 protons in the nucleus. Therefore, the atomic number of this element is 6!

Why do we care about atoms & elements again? All matter on Earth is made of elements… …& elements are made of atoms! Tennis BallsOur Bodies!Your Pencil

Atoms have an equal number of protons & electrons. # protons = # electrons = NO CHARGE Sometimes, an atom can be unstable. – This means that the number of electrons this atom has makes it too reactive to other atoms. So, what happens to an unstable atom? Pure sodium is highly reactive. It will burst into flames if exposed to the air or will burn through human flesh.

Ions Charged atoms with extra or fewer electrons than they have as a neutral atom They gain or lose electrons in order to become stable. A full electron level is considered stable.

Would this chlorine atom gain or lose electrons to become stable? A.Gain B.Lose Gain! There are 7 electrons in the outer shell, but 8 would make the atom stable.

These 3 atoms have the same number of protons, but a different number of neutrons. Are they the same atom? A.Yes B.No Yes! Remember! It’s the # of PROTONS that determines the type of atom. So, if these 3 atoms have the same # of protons, they’re the same atom.

Isotopes Uncharged atoms with a different atomic mass than the common element (because of a different # of neutrons)

Isotopes Some are radioactive & break down at a constant rate over time. Radioactive isotopes are used in carbon dating & some cancer treatments.

So, how do atoms form the molecules that build life? BONDING

Ionic Bonds Electrons are transferred between a metal & a non-metal – NaCl, CaS Strong force

Covalent Bonds Actually share electrons between non-metals – CO 2, NO 2 Strong force

Hydrogen Bonds Form between water molecules Very weak force

Molecules Two or more atoms bonded together – O 2, N 2, Cl 2 The physical & chemical properties of a molecule are very different than the elements alone! Atomic oxygen (O 1 ) doesn’t exist on Earth for very long, but it exists in space. The oxygen we breathe is O 2.

Compounds Two or more atoms of different kinds bonded together in definite proportions – H 2 O, CO 2 All compounds are molecules, but not all molecules are compounds!

Subscripts Written below the level of the line Signify the number of atoms in the molecule 1 Mg atom + 2 Cl atoms  MgCl 2 Polyatomic Ions: group together as one – Written in parenthesis – You must multiply through!

Subscripts Al(NO 3 ) 3 There is 1 Al, 3 N, & 9 O! (CH 3 ) 3 CH There are 4 C & 10 H!

Coefficients Written to the left of the molecule Signify the number of molecules 5NaCl  5 molecules of NaCl  10 total atoms 3NO 2 contains 3 N & 6 O! C 6 H 12 O 6 – Glucose 2C 6 H 12 O 6 – 2 Glucose molecules!