Basic Chemistry

BASIC CHEMISTRYATOMS, ELEMENTS AND HOW THEY BEHAVE

IN THIS UNIVERSE…..There is…….

•Matter – anything that has MASS and takes up space.

•Space – what is not matter.

•Which is there more of????

WHERE DID MATTER COME FROM?Big Bang

• Approx. 13 BYA• Produced enormous amounts of energy!• Energy eventually “chilled” enough to form basic building blocks of matter

• Evidence???• Expanding Universe• Red-shift• Background radiation

BUILDING AN ATOMAtoms = basic unit of matterMade of…

• Electrons (e-)• small, no mass, negatively charged

• Protons (p+)• Has mass, positively charged

• Neutrons (n0)

• Has mass, no (neutral) charge

ATOM STRUCTUREProtons and Neutrons are located near the center of the atom and form the NUCLEUS

Electrons orbit around the nucleus in specific electron orbitals/shells.

Why are electrons attracted to the nucleus?

What keeps the electrons from “crashing in?”

STRUCTURE OF AN ATOM

P+P+

N

N

e-

Nucleus

Orbit

e-

STRUCTURE OF AN ATOM

PP

N

N

e

e

Nucleus

Orbit

e

eee

e

e

e

e

e

EACH ORBIT IS A SPECIFIC

DISTANCE FROM THE NUCLEUS.

PP

N

N

e

e

Structure of an Atom

KEY POINT!!!!Atoms, can have DIFFERENT combinations of electrons, neutrons and protons!These different combinations makes the atoms BEHAVE differently and have different properties.

INTRODUCING THE ELEMENTS!

SO WHERE DID ALL THESE DIFFERENT ATOMS COME FROM????

Telling the story of matter….- Big Bang HUGE amount of energy released- Energy “chills” and starts to form basic building blocks

of matter- First atoms form Hydrogen and Helium.- Hydrogen attracted to other hydrogen Big balls of

hydrogen- FUSION REACTION (aka stars) smaller atoms fuse

together to form heavier elements (carbon, nitrogen, phosphorus sulfur).

- SUPER FUSION In supernovas even heavier elements are formed.

WHERE THIS LEAVES US!

Approx 5 BYA… - some leftover space debris (matter)

from star cycles start to coalesce in different ways

- Hydrogen collected in center starts a fusion reaction => our sun starts fusion

- Circling debris coalesces to form planets, asteroid belt, moons, etc.

WHAT WE HAVE ON EARTHAtoms can exist in varying forms on earth- Compounds

- Two or more different atoms bonded together- Ex. H20, CH4

- Elements- substances consisting of only one type of

atom. - A single atom is the smallest amount of an

element you can have. - Ex. O2, H2

ATOMIC THEORIES AND DISCOVERIES

Dalton: Late 19th century- thought the atom was nothing more than a tiny

indivisible sphere

Rutherford: Early 20th century- Nucleus contains protons and neutrons- Number of protons dictates which element it is.- Electrons circle nucleus in orbits.

ATOMIC THEORIES AND DISCOVERIES (CONT.)

Neils Bohr- Electron orbits

exist at only certain energy levels (distances) from the nucleus.

BOHR’S VIEW OF THE ATOM

Each orbit holds only a certain number of electrons

Orbit 1 – max 2Orbit 2 – max 8Orbit 3 - max 8

BOHR’S VIEW OF THE ATOMValence Electrons: - Electrons in the outermost

orbit- Determine how an atom

“behaves” - atoms with not completely full

valences tend to interact (bond) with other atoms.

BOHR’S VIEW OF THE ATOM

Elements with full “outer shells” do not react- Noble or “Inert” gases- He, Ne, Ar, Kr, Xe, Rn

FULL VALENCE = NON REACTIVE

NOT FULL VALENCE = REACTIVE!

THE PERIODIC TABLE

Key Points for what the periodic table tells us.Atomic number = number of protonsAtomic Mass=“approximate” number of protons + neutronsIf atom has a charge of zero, Electrons = Protons

HOW TO READ A PERIODIC TABLE

YOU TRY ITOxygen

Atomic # _______________

Atomic mass ____________

Number of

p+ ____________

n0 ____________

e- ____________

Sulfur

Atomic # _______________Atomic mass ____________

Number ofp+ ____________n0 ____________e- ____________

IONS

When we say “atoms” we typically mean a neutral charge

- number protons = number electrons

Sometimes and atom can gain or lose electrons!- now has a positive or negative charge =

ION!

ISOTOPESSometimes an atom of the SAME element can gain or lose neutrons

- does it change the charge?- does it change how it behaves?

Isotopes = atoms with the same number of protons and electrons but different neutrons

COMPOUNDSTwo or more atoms bonded together in a set proportion. Ie. CH4, H20, C6H12O6

MOLECULESSingle unit of a compoundContains more than one atom,

BUT can be the same type of atom (O2, N2)

COMPOUNDSTwo or more different atoms bonded together.Type of bond depends on the number of valence electrons of the atoms involved.

• Ionic•Covalent

Bonding Animations

TYPES OF BONDSIonic: one atom gives electrons to another, creates opposite charges

TYPES OF BONDSCovalent: atoms share electrons to get full valences

BONDING – DEPENDS ON VALENCE E-’S

Atoms will form bonds to get full valencesRemember:

1st level holds 2 electrons2nd level holds 8 electrons3rd level holds 8 electrons

ATOMS WORKING TOGETHER TO GET FULL VALENCES!Examples: Predict how/what type of bondNa (1Ve) bonds with Cl (7Ve’s)C (4Ve) bonds with 4H (1 Ve each)O (6 Ve) bonds with 2H (1 Ve each)

TYPES OF BONDS

Which do you think is stronger?•Ionic: two atoms attracted by opposite charges?

OR•Covalent: two atoms holding on to same electrons

MIXTURES VS. COMPOUNDSCompounds have different properties than any of the elements that make it up

Example:4 H2 (gas) + 2 O2 (gas) 4 H20 (liquid)

•Parts are Chemically bound•Definite proportions required

• Ex. H20 means there are always two hydrogen atoms per one oxygen atom

CHEMICAL FORMULAS

A chemical formula tells us three things:•What elements are involved•How many atoms of each you have•How many molecules you have

CHEMICAL FORMULAS

•Ex: 3C6H12O6

•This means there are 3 molecules of (C6H12O6) which is glucose

•1 molecule of (C6H12O6) contains 6 Carbon atoms, 12 Hydrogen atoms and 6 Oxygen atoms

•So how many H’s total are represented in the formula at the top?

MIXTURES VS. COMPOUNDSMixtures have ingredients that do not chemically bind to one another

•Mixture has same properties as ingredients

•No definite proportions needed•Can easily be separated•Types: solution, suspension, colloid

TYPES OF MIXTURESSolution – Homogeneous mixture

•equal composition throughout•2 or more substances; solvent and solute •Solute is individual ions or molecules•Solvent is what the solute is dissolved in.•Ex: Saltwater, sugarwater

TYPES OF MIXTURES

Suspension – heterogeneous•looks uniform when shaken or stirred;

•Separates upon sitting (no agitation)

•Ex. Blood, salad dressing

TYPES OF MIXTURES

Colloid – •Mixture of very tiny particles of dispersed in another substance;

•Suspended but do not settle out •Ex. Mayonnaise, fog, milk

THE MOST IMPORTANT INORGANIC MOLECULE OF LIFEWATER!

PROPERTIES OF WATER- Nearly all of life’s chemical reactions

happen in water.- Water is a pretty special molecule due to

some unique characteristics of the molecule

WATER- POLAR COVALENT MOLECULE•Share electrons but not equally

• slight (-) charge in the O• slight (+) charge in the H’s of water

HYDROGEN BONDING: WHAT’S HAPPENING?

Bio H

Because of the dipole (partial charges) created by the polar covalent bond H2O molecules are weakly attracted to one another

This attraction is called a H-bond

PROPERTIES OF WATER

Polarity of Water movie

PROPERTIES OF WATER

Cohesion•Water molecules stick to other water molecules

•Creates a high surfacetension

•Belly flop anyone?

Adhesion•Water molecules stick to other substances with partial charge

•Capillary action!

Properties of Water

PROPERTIES OF WATER Universal Solvent

Polarity of water allows it to interact with neighboring polar or ionic molecules

Dissolves or suspends many substances

What will not dissolve in water?

PROPERTIES OF WATER

Universal Solvent – making salt water

PROPERTIES OF WATEREXAMPLE NaCl + H2O Na+ + Cl- + H2O

oxygen attracts sodium hydrogen attracts chloride sodium & chloride separate as ionic

bonds are broken Is this a solution, suspension or

colloid?

Water has a high specific heat•Specific heat is the amount of energy needed to raise 1 gram of water 1 degree.

•Water absorbs a lot of energy before its temp goes up

•Keeps earth’s temperature stable!

Properties of Water

CONCEPT OF PH – SEE PH SCALE AND WORKSHEET