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

Understanding Basic Chemistry

• Atom – the smallest particle into which a substance can be broken by ordinary chemical means.– Parts of an Atom:

• Proton – in the nucleus and has a positive charge

• Neutron – in the nucleus and has a neutral charge

• Electron – in the orbital (shell, energy level) and has a negative charge

• Atomic Mass = protons + neutrons

• Atomic Number = protons

• Electrons usually equal the protons if the atom is neutral.

• Remember an atom is defined by it’s number of protons. If you change the protons you change the atom!!!!!!!!

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

• Oxidation Number – number of electrons an atom has gained or lost and the charge associated. Ex. Looking at the above valence of 7 the oxidation number is: -1

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

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

Molecule- Groups of non metal atoms bonded together by covalent bonds & acting as a group.

Compound – Two or more elements chemically combined ex. H2O

(Organelles- Basic structures within cells – has a specific function) (remember on the line not on a step?)

Cell - Basic Unit of living things.

Tissue- Tissues are groups of the same cells – they have a common function.

Organ- Composed of several different tissues working together.

Organ system - A group of organs working together to perform a major body process. Ex. Digestion.

Organism- (a group of organ systems in an individual) – any living thing – this would be multicellular (more than one cell)

• Population - (1 species ex. squirrels)

• Community - (2 or more species ex. Squirrels and maple trees)

• Ecosystem - (biotic and abiotic - meaning all the living and nonliving things in an area)

• Biome - (regional or global area ex. The tundra or a rain forest)

• Biosphere - the earth.

General Chemistry You Should Remember

Mixtures

• Mixtures – two or more substances not chemically combined – therefore they retain their own properties

Types of Mixtures:

1. Solutions – evenly combined mixture composed of:

• Solvent – does the dissolving ex. Water

• Solute – the substance being dissolved ex. Sugar

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

• Example sand in water (whole blood)

3. 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 (taking is negative)

• Cations have lost one or more electrons (giving is positive)

•

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 – and remember it is really an attraction.

Electrons shared equally between atoms produce nonpolar covalent molecules

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

Polar and Nonpolar Covalent 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 + DC → AC + DB

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

Additional Vocabulary

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

•

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

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

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

SUMMARYSUMMARY

1. The Atomic Number of an atom =

number of

protons in the nucleus. (or electrons in a neutral atom)

2. The Atomic Mass of an atom =

number of Protons + Neutrons in the nucleus.

3. Remember:

•Protons are positive,

•Neutrons are neutral

•electrons are negative.

4. Protons, Neutrons are in the nucleus and electrons are in the

shell.

5. The number of Protons =

Number of Electrons in a neutral atom or the atomic number.

6. A “normal” atom has a neutral charge

7. An atom that has given or taken electrons is called an

ion (cation gave….. Anion took)

8. An atom that has a different number of neutrons is called an

isotope

9. Electrons orbit the nucleus in shells/energy levels/orbitals.

10. Each shell can only carry a set number of electrons

11. Valence – number of electrons in the outer energy level. Example 7

12. Oxidation Number – number of electrons an atom has gained or lost and the charge associated. Ex. Looking at the above valence of 7 the oxidation number is: -1

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