Chemistry Introduction to Chemistry Honors Biology Ms. Kim.

Chemistry

Introduction to ChemistryHonors Biology

Ms. Kim

Composition of MatterComposition of Matter

Matter - everything in universe is composed of matter (“stuff”) Matter is anything that

occupies space or has mass Mass – quantity of

matter an object has Weight – pull of

gravity on an object

ElementsElements Pure substances that cannot be broken

down Made of a single type of atom (group of

atoms of the same type) More than 100 elements (92 naturally

occurring)

ElementsElements Atomic # of an element

Equals the # of protons AND the # of electrons Unique for each element

Mass # of an element Equals the SUM of protons and neutrons

Therefore….Protons + Neutrons = Mass #

Mass # - Atomic # = Neutrons

CHONPSCHONPS All living things are made up of 4 Biological macromolecules (which we

will be talking about later). Carbohydrates Lipids Proteins Nucleic Acids

Biological macromolecules are made almost entirely of just 6 elements: Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N) Phosphorus (P) Sulfur (S) CHNOPS

The most important element is CARBON!

96% of the mass of an organism is composed of 4 elements (carbon, hydrogen, oxygen (65%) and nitrogen “CHON”)

Each element unique chemical symbol Consists of 1-2 letters First letter is always

capitalized

AtomsAtoms

Smallest and simplest piece of matter

Atom have 3 subparticles: Protons (Positive +) Neutrons (Neutral 0) Electrons (Negative -)

The NucleusThe Nucleus

Middle of the atom (central core)

Holds positive charged protons and neutral neutrons

Positively charged

Contains most of the mass of the atom

The ProtonsThe Protons All atoms of a given element have

the same number of protons

#of protons = the atomic number

# of protons (+’s) = # of electrons (-’s) (in a neutral atom)

The NeutronsThe Neutrons The number varies slightly among

atoms of the same element

Different number of neutrons produces isotopes of the same element

Isotopes = an element with the same # protons, but different # neutrons

Ex: C12 vs. C14

Isomers = compounds with the same molecular formula, but different structures

Isotopes \ IsomersIsotopes \ Isomers

Atomic MassAtomic Mass

Protons & neutrons are found in the nucleus of an atom

Protons and neutrons each have a mass of 1 amu (atomic mass unit)

The atomic mass of an atom is found by adding the number of protons & neutrons in an atom

What is the atomic mass of an oxygen?

Practice Problems!Practice Problems!

1. How many protons does a sodium (Na) atom have?

2. How many neutrons does a fluorine (F) atom have?

3. What is the atomic mass for oxygen (O)?

4. What is the atomic number for phosphorus (P)?

The ElectronsThe ElectronsNegatively charged high

energy particles with little or no mass

Travel at very high speeds in different energy levels Energy levels are

different distances from the nucleus

Electrons in the same energy level are approximately the same distance from the nucleus

Outer energy levels have more energy than inner levels

Each level holds only a certain number of electrons

Energy Levels

Electron ShellElectron Shell

Shells: Inner most can hold at most 2 e-

Outer most can hold at most 8 e-

Third outer most can hold at most 8 e-

Elements want to have full shells, because this makes them stable!

Carbon (neutral) Atomic # = 6 6 total electrons

2 electrons fill the inner most shell 4 will be in the outer most shell This means Carbon has 4 VALENCE electrons Can bond to 4 other atoms!

Electron Shell

Periodic TablePeriodic Table Elements are arranged by their atomic

number on the Periodic Table

The horizontal rows are called Periods & tell the number of energy levels

Vertical groups are called Families & tell the outermost number of electrons

CompoundsCompounds

Most atoms do not exist by themselves

Atoms combined with other atoms to form compounds

CompoundsCompounds

A compound is a pure substance made up of atoms of two or more elements 2 types: molecules or ionic

compounds

Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound

Compounds : Examples Have different properties than individual

elements Ex: NaCl = 1 sodium + 1 chloride table

salt Ex: H20 = 2 hydrogen + 1 oxygen water Ex: NaOH = 1 sodium + 1 oxygen + 1

hydrogen Ex: CO2 = 1 carbon + 2 oxygen

CompoundsCompounds

CompoundsCompounds

What happens when the ratio of atoms changes?

H20 vs. H2O2

When the ratio of elements in a compound changes, the physical and chemical properties change too

MoleculesMolecules Molecule is two or more atoms held together by covalent

bonds. Almost all of the substances that make up organisms, from lipids to nucleic acids to water, are molecules held together by covalent bonds.

A compound is a type of molecule. All compounds are molecules, but all molecules are NOT compounds.

Molecule Examples: H2O, O2, O3

Compound Examples: NaCl, H2O

Chemical FormulasChemical Formulas

2H202 2H2O + O2

Subscript after a symbol tell the number of atoms of each element

H20 has 2 atoms of hydrogen & 1 atom of oxygen

Coefficients before a formula tell the number of molecules

3O2 represents 3 molecules of oxygen or (3x2) or 6 atoms of oxygen

BondsBonds Molecular “glue” Holds atoms together to

form compounds Valence electrons are

involved in bonding Valence electrons =

electrons on outer most energy level.

Atoms are most stable when their outer most energy level is filled

What holds atoms together? Atoms are held together by chemical

bonds

Goal: to fill outer electron shell…so atoms BOND together (share or give away/take electrons) to get a full outer shell

2 main types: Ionic bonds Covalent bonds

BondsBonds

Single

Double

Triple

Bonds SIZE decreases as you increase # of bonds

Bonds STRENGTH increases as you increase # of bonds

Formed when two atoms share one or more pairs of electrons. (‘co’ means ‘together’)

When two or more atoms are joined by covalent bonds, we call this a molecule Very strong Single, double, triple bonds

H = 1 bond O = 2 bonds N = 3 bonds C = 4 bonds

Covalent Bonding Covalent Bonding

Because positive and negative electrical charges attract each other ionic bonds form

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

Atoms lose or gain electrons If an atom loses electrons becomes

positively charged (+) If an atom gains electrons becomes

negatively charged (-)

Atoms that have gained or have lost electrons are ions Ex: Salt (NaCl)

Ionic BondsIonic Bonds

Cations & AnionsCations & Anions Cation = when an atom loses an electron, it

becomes more positively charged Positive Ion = Cation Remember: Cats have PAWS and are POSITIVE Ex: Removing an electron from a K (potassium)

atom will….create a POSTITIVE ION = CATION

Anion = When an atom gains an electron, it becomes more negatively charged Negative Ion = Anion Ex: If a Cl (chlorine) atom gains an electron…creates

a NEGATIVE ION = ANION

States of MatterStates of Matter Atoms are in constant motion (called

kinetic energy)

The rate at which atoms or molecules in a substance move determines its state

Level of OrganizationLevel of Organization Subatomic particles (p+, e-,

n0)

atom (O)

Element (O)

molecule (O2)

macromolecules (lipid)

Cell (blood cell) <--life begins here

Tissue (epithelia tissue)

Organ (lung)

Organ system (Respiratory System)

Organism (Panthera leo (lion))