Chemistry of Health and Enviornment

chapter 1-6

element

A pure substance that cannot be broken down into other substances by chemical or physical means

molecule

two or more atoms held together by covalent bonds

Mass

A measure of the amount of matter in an object

Weight

A measure of the force of gravity on an object

Density

the ratio of the mass of a substance to the volume of the substance

Concentration

A measurement of how much solute exists within a certain volume of solvent

H

Hydrogen

He

Helium

define matter

Anything that has mass and takes up space

Define solid

Definite shape and volume

Define liquid

definite volume, indefinite shape

Define gas

No definite shape or volume

physical property

a characteristic that can be observed or measured without changing the identity of the substance

physical change

process in which a substance changes its physical appearance but not chemical composition

chemical property

characteristic of a substance that describes the way the substance undergoes change

chemical change

process in which a substance undergoes a chemical composition

pure substance

a single kind of matter that cannot be separated into other kinds of matter by any physical means

Mixture

a physical combination of two or more substances

Compound

a pure substance that can be broken down into other pure substances

Atom

Smallest particle of an element

Li

Lithium

Be

Beryllium

B

Boron

C

Carbon

N

Nitrogen

O

Oxygen

F

Fluorine

Ne

Neon

Na

Sodium

Mg

Magnesium

Al

Aluminum

Si

Silicon

P

Phosphorus

S

Sulfur

Cl

Chlorine

Ar

Argon

K

Potassium

Ca

Calcium

Neutron

A small particle in the nucleus of the atom, with no electrical charge

Electron

A subatomic particle that has a negative charge

Proton

positively charged particle

atomic number

the number of protons in the nucleus of an atom (the number of electrons)

mass number (atomic mass)

number of protons plus the number of neutrons in an atom of an element

isotopes

Atoms of the same element that have different numbers of neutrons

Isotope X has 23 protons and 28 neutrons. What is it's atomic mass?

23 + 28 = 51

Orbitals

what electron fill as energy increases

S=1 P=3 D=5 F=7

Determine electron configuration using the periodic table

# of columns in each area= total # of electrons in the orbital

S=2 P= 6 D=10 F=14

Define valence electrons

electrons in the outermost energy level ( most # of valence electrons is 8)

English to Metric Conversions

1in= 2.54cm 100cm=1m 1000ml=1l 2.2kg=1lb

Convert numbers to scientific notation

16,000 = 1.6 x 10 ^4

Kelvin to Celsius

C=K-273

Celsius to Fahrenheit

F= 9/5 (C+32)

Fahrenheit to Celsius

C=5/9(F-32)

Celsisus to Kelvin

K= C + 273

explain chemical formulas

notation made up of the symbols of the elements present in a compound or molecule

Principles of ionic compounds

have high melting points and are good conductors of electricity in their liquid state

Principles of molecular compounds

have much lower melting points and don't conduct electricity

Chemical Bonds

the attractive forces that hold atoms together

ionic bond

Formed when one or more electrons are transferred from one atom to another

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

Define octet rule

Chemical compounds tend to form so that each atom, by gaining, losing, or sharing electrons, has an octet of electrons in its highest occupied energy level.

Except H,He, Li, Be, B which only contain 2 Valence electrons (s only)

Predict ionic charge

Group 1A has 1 VE it will loose on electron and become a cation

Group 2A has 2 VE it will loose both electrons and become

2+ (cation)

Group 6A HAS 6 VE it will gain 2 electrons 2- (anion)

only works for group A's

Anion

A negatively charged ion due to gain of electrons

Cation

A positively charged ion due to loss of electrons

Lewis Dot Structure

diagram of a molecule using dots to represent valence electrons

Write formulas for ionic compounds

Aluminum and oxygen

Al (Group3A) looses 3 Al3+

O (Group6A) gain 3 O2-

Al2O3

Write formulas for ionic compounds

-Positive ion first, then negative ion

-Positive charge must balance negative charge

-Paranthesis around polyatomic ions that appear more than once

FeCl2 and FeCl3

Iron (II) Chloride and Iron (III) Chloride

Identify polyatomic ions

A group of atoms (held together by covalent bonds) that react through the loss or gain of electrons

Calculate molar masses of ionic compounds

Molar Mass of Al(OH)3

Al= 26.98 *1

O=16 * 3

H=1 *3

MM= 78g/mol

NO3-

nitrate

NO2 -1

nitrite

NH4 +1

ammonium

SO4 -2

sulfate

SO3 -2

Sulfite

OH-

hydroxide

PO4 -3

phosphate

PO3 -3

phosphite

CO3 -2

Carbonate

HCO3-

hydrogen carbonate

Describe and explain the principles of covalent bonding

2 nonmentals that share valence electrons to form a common orbital between atoms.

this is shown by a pair of dots or dash line (bond)

Bonding electrons

pairs of VE that share atoms

Nonbonding electrons

Pairs of VE that do not share atoms

Single bond

2 atoms share 1 pair of electrons

ex. H-H

Double bond

2 atoms share 2 pairs of electrons

ex O=C=O

triple bond

2 atoms share 3 pairs of electrons

ex; N=N

Identify VE and Bond formation

O= 6 valence electrons (Group 6A) its missing 2 VE=max 2 bonds

Name covalent Compounds using IUPAC nomenclature

What is the proper formula for carbon chloride?

CCl4 or Cl4C. C=4 VE. Cl=7 VE

Cl has a higher electronegativity than C

define electronegativity and explain effect on bonding

measure of relative attraction that atoms has for the shared electrons in a bond

higher the electronegativity the greater the attraction of shared electrons

electronegativity increases from left to right of the periodic table

Nonpolar convalent bond

Covalent bond with equal sharing of electrons between 2 atoms (electronegativity valves are equal)

Electronegativity difference = 0.4 or less

Polar Covalent Bond

Covalent bond with unequal sharing of electrons between 2 atoms (electronegativity valves are unequal)

Electronegativity difference = greater than 0.4 to 1.5

Chemical reactions

process in which at least 1 new substance is produced as a result of chemical change

combination reaction

single product is produced from 2 or more reactants

ex X + Y → XY

decomposition rection

single reactant is converted into 2 or more simpler substances

ex, xy → x + y

displacement reaction

reaction in which an atom displaces an atom or group od atoms from a a compound

ex. x+yz→ y + xz

exchange reaction

reaction in which 2 substances exchange parts with one another to form 2 different substances

ex ax+by →ay +bx

combustion reactions

reaction between a substance and oxygen that evolves into heat and light

oxidation

a reactant looses on or more electrons

reduction

a reactant gains one or more electrons

OIL RIG

oxidation is loose

Reduction is gain

oxidation- reduction reaction

reactions with a transfer of electrons from one reactant to another reactant