Structure of the Atom B. Suspension : mixture where particles are - - PDF document

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Why is chemistry important? Chemistry is related to Biology because all the processes that go on in our world and in your body are a result of chemical reactions.

• photosynthesis
• digestion
• metabolism

Biochemistry: chemistry of living organisms

CHEMISTRY OF LIFE

Everything around us is made up of matter .

Matter: anything that has mass and volume Mass: amount of matter in an object Volume: amount of space and object takes up Weight: force of gravity on mass

States of matter

• 1. Solid: definite shape and volume
• 2. Liquid: indefinite shape, definite volume
• 3. Gas: indefinite shape and volume

Classification of Matter Classification of matter

• I. Pure substances: a substance that is identical throughout
• A. Element: composed on only one type of atom

Ex: Na, Pb, Cl, etc …….

• 109 elements
• 90 natural
• 19 synthetically made in lab, basically radioactive
• most solid
• represented by symbols (from Latin)

Ex: lead Pb plumbus Sodium Na natrium Iron Fe ferrium

• B. Compound: two or more elements chemically

combined in a definite proportion Ex: H2O, H2O2 CO2, CO O2, O3 ** cpds have different properties than original elements that make them Ex: NaCl sodium: metal, poison Chlorine: gas, poison

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• II. Mixture:

two or more substances (element or compound) mixed but not chemically combined

• original substances keep their identities and can be

separated out by physical means Ex: salt water – boil off water and collect salt Ex of mixtures: salad dressing rocks, sand, water, blood, earth’s atmosphere (O, N, CO2, Ar, etc)

Two types Mixtures

• A. Solution: mixture where substances are equally distributed

and appear as one substance Components of a solution Solute: substance being dissolved Solvent: substance doing dissolving ex: ice tea mix in water ex: 0.85% NaCl in plasma (water component of blood) Aqueous solution: water is UNIVERSAL SOLVENT when two same states of matter: solvent is substance in larger amount

• B. Suspension:

mixture where particles are too small to settle and stay suspended due to movement

• f water molecules

Ex: milk Example of solution and suspension: blood: salt in water - solution blood: cells in saline - suspension

Structure of the Atom

Atom: basic unit of matter, pure substance Subatomic structure 1. Protons – positive, inside nucleus 2. Neutrons- neutral, inside nucleus

• 3. Electrons- negative, outside nucleus

equals the number of protons ( size of nucleus compared to whole atom is like pea in giants stadium ) Atomic number = protons Protons = Electrons Atomic mass = protons + neutrons

Isotopes: different form of the same element due to different number of neutrons

• most radioactive (elements with unstable nuclei which

break down and emit particles)

Ex: C 12, C13, C14 6 protons 6 protons 6 protons 6 neutrons 7 neutrons 8 neutrons H1 H2 H3 protium deuterium tritium 1 proton 1 proton 1 proton 0 neutrons 1 neutron 2 neutrons

Uses of Isotopes

• Study age of fossils and rocks C14
• Radiation therapy: cobalt 60, cancer

carbon 14, brain tumors

• Medical tests:

cobalt 60

Thallium, stress tests Iron 59, blood circulation Iodine, thyroid tests

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Bonding

Chemical bond: process if joining atoms in a compound

• Electrons are subatomic particles involved in bond
• Goal of bond: to complete outer shell and become

stable

• To form a compound electrons:
• gain
• lose
• share

Bonding Basics

Bonding Basics

• Atoms try to fill valence

shell (orbital) to become stable

• H and He: need 2 valence

electrons

• All other atoms: need 8

valence electrons

• Metals lose electrons
• Non metals gain electrons

Types of Bonds

• 1. Ionic:

transfer of electron between metal and non metal

• metal gives electrons to

non metal

• ions (charged atoms)

formed Ex: NaCl, MgBr2

• strong magnetic attraction

keeps compound together

Types of Bonds

• 2. Covalent:

two non metals share electrons

• called molecules

ex: H2O, CO2

• interparticular forces

keep atoms together

Types of Bonds

• 3. Hydrogen:

weak chemical attraction between polar molecules

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WHENEVER BOND IS FORMED A CHEMICAL CHANGE TAKES PLACE Chemical reaction (change): process in which a chemical change occurs due to bonding Ex: decaying of apples digestion of food burning of coal decomposition of plants rusting of iron EVERYTHING THAT OCCURS IN LIVING ORGANISMS IS A RESULT OF CHEMICAL REACTIONS.

WATER AND SOLUTIONS

• universal solvent in organisms
• ne of few liquid compounds found naturally on earth, most solid
• expands in solid form
• covers > 75% of earth
• most abundant compound in living organisms

(human body ~ 70%)

• most important compound in organisms
• cells surrounded by it
• filled with it
• cellular events occur in it)
• carries or dissolves other substances

Properties of Water

1. Polar molecule (polarity)

Will carry or dissolve other substances in it which are vital for life.

• Hydrophilic: substances that

dissolve rapidly in water *Generally polar molecules

• r ions (unlike charges

highly attracted to each

• ther)
• Hydrophobic: substances that

are insoluble in water *Generally non-polar molecules (water molecules are more attracted to each other than the non polar molecules)

• 2. Cohesion/Adhesion
• Cohesion: attraction of same substances of same kind

(water to water)

• Adhesion: attraction of water to other materials
• oxygen end: negative charge
• hydrogen end: positive charge.

The hydrogens of one water molecule are attracted to the oxygen from other water

• molecules. This attractive force is what gives

water its cohesive and adhesive properties. 3. Surface Tension: cohesion of water molecules at the surface of a body of water

• Each molecule in the water drop is attracted to

the other water molecules in the drop.

• This causes the water to pull itself into a shape

with the smallest amount of surface area, a bead (sphere).

• All the water molecules on the surface of the

bead are creating surface tension. (like a large group of people tightly holding hands) 4. Capillary Action adhesion of water molecules to other substances which allow it to be drawn up the surface

• f the other subst.

Ex: meniscus plants pull water into themselves water “climbing” up a straw

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5. Stores heat efficiently

• absorbs a lot of energy before it will raise its

temp.

• retains its heat longer than many other substances
• this property keeps temperature fluctuations to a

minimum in order support life on land and in water

IONS AND LIVING CELLS

Salt is a very important polar molecule.

• When mixed with water, the ionic bonds are broken and the

Na and Cl ions separate (dissociation)

• The charged ends of each ion are attracted to the polar ends of

water

• This is very important because ions such as Na, Cl, K, and Ca

are involved in many reactions inside the cell

Ionization

Process of water (non-ionic) being converted into ions Result: Separate H+ and OH- ions H+ combines with water to make H3O+ ion

pH: number of H ions in a solution

Acid: any compound that releases H ions into water

• H3O+ (hydronium ion is formed)

ex: hydrochloric acid in water HCl  H+ + Cl- **** Most reactive ion due to no electrons- attacks bonds in many molecules Base: compound that releases OH- ions into water Ex: NaOH  Na+ + OH-

• Neutralization reaction: production of

H2O from mixture of strong acid and base

neutral H = OH acidic H > OH basic, alkaline H < OH Buffer solution which resists changes in pH when small quantities of an acid or an alkali are added to it

• Important in maintaining pH in organisms

The pH scale

Acid: below ph 7 (more H ions) Base: above pH 7 (more OH ions) IMPORTANCE OF PH:

• most reactions in organisms can
• nly occur with enzymes
• enzymes very pH specific

***failed kidney function is most

• ften reason for inability to

maintain normal blood pH