Chapter 2 Chemistry of Life

Chapter 2 Chemistry of Life

• Can you list the levels of organization?

Matter

• Matter – Anything that has mass and takes up space – made up of atoms.

States of matter–Solid – has definite shape and volume

–Liquid – has definite volume, changeable shape

–Gas – has changeable shape and volume

Atom - The smallest particle into which a substance can be broken by ordinary chemical means.

Remember an atom has a nucleus that consists of neutrons (neutral) and

protons (positive)

Electrons (negative) are found orbiting the nucleus

Levels Reviewed

Element – Groups of the same type of atom

Compound – Two or more elements chemically combined ex. H2O

MOLECULE- GROUPS OF ATOMS BONDED TOGETHER & ACTING AS A GROUP

ORGANELLES- BASIC STRUCTURES WITHIN CELLS – has a specific function

CELL- BASIC UNIT OF LIVING ORGANISMS

• TISSUE- TISSUES ARE GROUPS OF CELLS WITH A COMMON FUNCTION.

• ORGAN- OFTEN LARGE AND COMPOSED OF SEVERAL DIFFERENT TISSUES

• ORGAN SYSTEM- A GROUP OF ORGANS CARRYING OUT A MAJOR BODY PROCESS

• ORGANISM- (A GROUP OF ORGAN SYSTEMS IN AN INDIVIDUAL) – any living thing

Mixtures • Mixtures – two or more

substances not chemically combined – therefore they retain their own properties

• Solutions – evenly combined•Solvent – does the dissolving ex. Water

•Solute – the substance being dissolved ex. Sugar

• Suspensions –The particles will spread out and eventually settle – large particles (saturated, unsaturated, and supersaturated)

•Example sand in water (whole blood)

• Colloid – a mixture that has medium particles – held in solution by their association with water

•ex. Liquid jello….. Mayonnaise

Mixtures Compared with Compounds

• No chemical bonding takes place in mixtures

• Most mixtures can be separated by physical means

• Mixtures can be heterogeneous or homogeneous

• Compounds cannot be separated by physical means

• All compounds are homogeneous

Writing Chemical Equations• The left side of an equation is

called the reactants.• The right side of an equation is

called the products• An arrow separates the reactants

from the products. The arrow is called a “yields” sign

Ex. Na + Cl NaCl

TYPES OF BONDS(Bonds store energy)

IONIC BONDS- ELECTRONS ARE TRANSFERRED FROM ONE ATOM TO ANOTHER AND IONS ARE FORMED

• Ions are charged atoms resulting from the gain or loss of electrons

• Anions have gained one or more electrons

• Cations have lost one or more electrons•

COVALENT BONDS- WHEN ATOMS SHARE ELECTRONS

(the strongest bond)e.x. Peptide bonds – between

C and N in proteins

HYDROGEN BONDS- A BOND BETWEEN HYDROGEN AND 2 SMALL ELECTRONEGATIVE

ATOMS ex. F, N, O (the weakest bond)

Electrons shared equally between atoms produce nonpolar molecules

Unequal sharing of electrons produces polar molecules (ex. Water!) (unequal causes a “charge” on each molecule)

Polar and Nonpolar Molecules

Types of Reactions• Chemical Reactions – the process of

breaking down chemical bonds and/or forming new ones (a chemical equations shows this)– To do this an activation energy is needed (

the energy that is needed to get the reaction going)• Exothermic – there is a net release of

energy (it feels warm)• Endothermic – there is a net absorption

of energy (feels cool)

Type of Reaction

Definition Equation

Synthesis

Decomposition

Single Replacement

Double Replacement

.

A = Red B = Blue C = Green D = Yellow

A + B → AB

AB → A + B

AB + C → AC + B

AB + CD → AC + BD

Two or more elements or compounds combine to make a more complex substance (ex. Dehydration synthesis – takes H2O away)

Compounds break down into simpler substances (ex

hydrolysis – puts H2O back)

Occurs when one element replaces another one in a compound

Occurs when different atoms in two different

compounds trade places

Identifying Chemical Reactions

____ P + O2 → P4O10 ____ Mg + O2 → MgO

____ HgO → Hg + O2 ____ Al2O3 → Al + O2

____ Cl2 + NaBr → NaCl + Br2 ____ H2 + N2 → NH3

2. Use colored pencils to circle the common atoms or compounds in each equation to help you determine the type of reaction it illustrates. Use the code below to classify

each reaction.

S = Synthesis D = Decomposition SR = Single Replacement DR = Double Replacement

____ Na + Br2 → NaBr ____ CuCl2 + H2S → CuS + HCl 

____ HgO + Cl2 → HgCl + O2 ____ C + H2 → CH4

____ KClO3  →   KCl  +  O2  ____ S8 + F2 → SF6

____ BaCl2   +   Na2 SO4 →     NaCl   +   BaSO4

Types of Reactions1. Synthesis – small molecules are

combined into larger molecules – always involves the formation of new chemical bonds

• Ex. A + B AB

Ex. Dehydration synthesis (condensation) – the formation of complex molecules by the removal of H2O

A-B-C-H + HO-D-EA-B-C-D-E + H20

• Anabolism – Energy requiring building phase of metabolism in which simpler substances are combined to form more complex substances

2. Decomposition – breaks large molecules into smaller ones

AB A + B–Ex. Food broken down–If water is used to breakdown the bonds then it is called hydrolysis (opposite of dehydration synthesis)

Ex A-B-C-D-E + H20 A-B-C-H + HO-D-E

• Ex Hydrolysis – is an example of a decomposition reaction where water is added back into the molecule

• Catabolism – Process in which living cells break down substances into simpler substances

Additional Vocabulary

• Valence – number of electrons in the outer energy level. Ex. 7

• Oxidation Number – number of electrons an atom has gained or lost and the charge associated. Ex. Looking at the above valence: 1-

• Octet Rule - filling the outer energy level to 8 electrons (exception is the first energy level that can only hold two electrons)