BASIC
CHEMISTRY
ATOMS, 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 ATOM
Atoms = basic unit of matter
Made of…
• Electrons (e-)
• small, no mass, negatively charged
• Protons (p+)
• Has mass, positively charged
• Neutrons (n0)
• Has mass, no (neutral) charge
ATOM STRUCTURE
Protons 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
e-
P+
Orbit
N
P+
N
e-
Nucleus
STRUCTURE OF AN ATOM
e
e
e
e
e
Orbit
e
N
P
Nucleus
P
N
e
e
e
e
e
Structure of an Atom
e
N
P
P
N
e
EACH
ORBIT IS A
SPECIFIC
DISTANCE
FROM THE
NUCLEUS.
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 EARTH
Atoms 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 2
Orbit 2 – max 8
Orbit 3 - max 8
BOHR’S VIEW OF THE ATOM
Valence 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 protons
Atomic Mass
=“approximate” number of protons + neutrons
If atom has a charge of zero, Electrons = Protons
HOW TO READ A PERIODIC TABLE
YOU TRY IT
Oxygen
Atomic # _______________
Atomic mass ____________
Number of
p+ ____________
n0 ____________
e- ____________
Sulfur
Atomic # _______________
Atomic mass ____________
Number of
p+ ____________
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!
ISOTOPES
Sometimes 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
COMPOUNDS
Two or more atoms bonded together in a
set proportion. Ie. CH4, H20, C6H12O6
MOLECULES
Single unit of a compound
Contains more than one atom,
BUT can be the same type of
atom (O2, N2)
COMPOUNDS
Two 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 BONDS
Ionic: one atom gives electrons to
another, creates opposite charges
TYPES OF BONDS
Covalent: atoms share electrons to get full
valences
BONDING – DEPENDS ON VALENCE E-’S
Atoms will form bonds to get full
valences
Remember:
1st level holds 2 electrons
2nd level holds 8 electrons
3rd level holds 8 electrons
ATOMS WORKING TOGETHER TO
GET FULL VALENCES!
Examples: Predict how/what type of
bond
Na (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. COMPOUNDS
Compounds 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. COMPOUNDS
Mixtures 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 MIXTURES
Solution – 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 LIFE
WATER!
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?
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
Bio H
PROPERTIES OF WATER
Polarity of Water movie
PROPERTIES OF WATER
Cohesion
•Water molecules stick to other water
molecules
•Creates a high surface
tension
•Belly flop anyone?
Properties of Water
Adhesion
•Water molecules stick to other
substances with partial charge
•Capillary action!
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 WATER
EXAMPLE 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?
Properties of Water
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!
CONCEPT OF PH – SEE PH SCALE
AND WORKSHEET