Bellringer – November 12, 2014

Look at the Periodic Table:1)What does the Au stand for?2)What atomic number is aluminum and what is

it’s symbol?3)What 6 elements are WE mostly made up of?

Look at the periodic table and take a guess!

ChemistryIntroduction to Chemistry

Honors BiologyMs. 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

Chemistry of Life• All matter is composed of tiny particles called

atoms.• There are 109 types of atoms - a substance made

up of one kind of atom is called an element. • An atom is the smallest part of an element that

still has the properties of that element.

Atomic Structure Each atom is made up of smaller

parts called protons, electrons and neutrons. Protons and neutrons are found in the central portion of the atom called the nucleus.

Protons (+) in nucleus

Neutrons (0) in nucleus

Electrons (-) in a cloud outside!

There are SIX elements necessary for life – C – Carbon H – HydrogenN – Nitrogen O – OxygenP – Phosphorous S- Sulfur

CHNOPS

•The most important element is CARBON!

Elements• Elemental Symbol

– Unique one/two letter symbol

• Atomic # of a neutral element – Equals the # of protons AND the # of electrons– Unique for each element

• Atomic Mass #-– Avg. mass of an atom of the element (AMU)– Equals the SUM of protons and neutrons

Therefore….Protons + Neutrons = Mass #

Mass # - Atomic # = Neutrons

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 \ Isomers

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

– Ex: C-12 vs. C-14

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

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 Electrons

Negatively charged high energy particles with little or no mass

Travel at very high speeds in different energy levelsEnergy levels are

different distances from the nucleus

Electron 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!• The electrons on the most outer shell is called VALENCE electrons• EXAMPLE: 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

Molecules and Compounds

• Molecules – 2+ atoms bonded together – O2 for Oxygen

• Compound – 2+ elements bonded together - CO2 for carbon dioxide and NaCl for sodium chloride

Compounds

• 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

Compounds

• 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

Molecules

• 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

BondsBondsMolecular “glue” Holds atoms together to form

compoundsValence 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

• 3 main types:– Ionic bonds– Covalent bonds– Hydrogen bonds

Covalent Bonding • 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– Covalent bonds are Very

strong

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

Ionic Bonds• 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)

Cations & 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 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))