Basic Chemistry

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Basic Chemistry

• Atoms, Elements and How They Behave

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Start Small End Big

• Atoms ? Elements ?
• Compounds ? Cells ?
• Tissues ? Organs ?
• Organ Systems ?
• Organisms

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ATOM
Smallest amount of an element that still has the
properties of that element. Made up of
- Protons, p, Charge of 1
- Electrons, e-, charge of -1
- Neutrons, n, charge of 0
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Structure of an Atom
e
Orbit Area outside nucleus where electrons are
in constant motion
N
P
Nucleus Center of atom, where protons and
neutrons are located
P
N
e
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Orbits spin and rotate in three dimensions.
Structure of an Atom
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Orbits spin and rotate in three dimensions.
Structure of an Atom
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Each Orbit is a specified distance from the
nucleus.
Structure of an Atom
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Structure of an Atom
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Structure of an Atom
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Each type of atom has its own number of e-, p and
n
Structure of an Atom
-
e
N

P

P
N
-
-
e
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The different combination of p, n and e- make
each element unique
Structure of an Atom
-
e
N

P

P
N
-
-
e
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Normally, all the of the protons and the -
from the electrons balance out and the overall
charge of the atom is zero.We call this a
neutral atom.
Structure of an Atom
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What if an atom loses an electron?
Structure of an Atom
-
e
e
N
N

P
P

P
P
N
N
- Atom becomes positive
-
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Structure of an Atom
What if an atom gains an electron?
-
e
N

P

P
N
- Atom becomes negative
-
-
e
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Any charged atom is called an ion
Structure of an Atom
- Positive ions are called cations
- Negative ions are called anions
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The Periodic Chart
Atomic number is the number of protons
Atomic Mass is the number of protons neutrons

• Assume electrons protons
• (except ions)

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Atomic Mass Protons Neutrons
Why dont the electrons figure in?
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Drawing Atoms
Each orbit can hold a maximum number of
electrons. - Orbit 1 holds a max of 2 - Orbit
2 holds a max of 8 - Orbit 3 holds a max of
8 You must fill the inner orbits before adding
electrons to the outer orbits.
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Examples
12 Mg 24
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Examples

• Sodium
• 11
• Na
• 23

29 Cu 63
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Valence electrons

• Electrons in outer most orbit
• Atoms want a complete outer orbit
• They will bond with atoms that fill the orbit

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Examples

• Look at the column on periodic table to figure
  out valence electrons
• Na __________ Cl ____________

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Examples

• Look at the column on periodic table to figure
  out valence electrons
• C __________ N____________

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Main Elements in Human Body

• Oxygen
• Carbon
• Hydrogen
• Nitrogen

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Compounds

• Two or more atoms bonded together in a set
  proportion
• H20 vs. H2O2
• what is different?

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Compounds

• Parts are chemically bound together
• Definite proportions required
• Properties of a compound are different from the
  properties of the elements that make up that
  compound

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Mixtures

• Mixtures have ingredients that do not bind
  chemically with each other
• Each ingredient keeps its own properties
• Definite proportions not required
• 3 Types solution, suspension, colloid

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Mixtures

• Solution
• Homogeneous (even throughout)
• Solute (dissolved substance) completely dissolves
  in solvent (liquid)
• Transparent
• Doesnt filter
• Example - salt water

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Mixtures

• Suspension
• heterogeneous
• May look homogeneous if shaken but particles will
  settle.
• Opaque (murky)
• Can be filtered
• Example dirt stirred into water

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Mixtures

• Colloid
• Heterogeneous BUT does not settle
• Sort of in between the other two.
• Appears translucent (let light through but image
  is not sharp)
• Does not filter out.
• Example - milk

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Mixtures vs. Compounds
Look at your notes What are three big
differences between Mixtures and Compounds?
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Types of bonds that form Compounds

• Ionic Bond- One atom gives an electron to the
  other

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IONIC

• Creates opposite charge that holds atoms together

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Types of bonds that form Compounds

• Covalent- each atom shares electrons with the
  other

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Chemical Reactions

• Change in the arrangement of atoms that creates a
  different substance

A B ? C synthesis reaction A ? B C
decomposition A B ? C D Displacement
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Chemical Reactions

• Reactants The stuff you start with
• Products The stuff you end up with

A B ? C
Reactants
Products
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Chemical Reactions
Al O2 ? Al2O3
C2H6 O2 ? CO2 H2O
H20 ? H OH-
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Properties of Water

• Water is held together with special covalent bond
  called polar covalent bond
• - Means water has poles, or ends.
• - O is the negative end
• - Hs are the positive ends

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Properties of Water
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Properties of Water

• Cohesion Water molecules stick together because
  of charges

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Cohesion

• Creates Surface tension
• - allows stickbugs to walk on water!

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Adhesion

• Water molecules stick to other charged substances
  like glass

Glass stirring rod
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Water is the Universal Solvent

• Anything with a charge will attract water
  molecules and dissolve
• Ionic and polar molecules have charge
• Nonpolar molecules (like fat) do not have charge
  and will not dissolve

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Acids and Bases

• Acids a chemical that when dissolved in water
  releases a hydrogen ion (H)

HX (in water) ? H X-
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Properties of Acids

• Taste sour think of lemon
• Turn litmus paper from blue to red
• Corrode Metals
• Examples Sulfuric Acid, Lemon Juice, Battery
  Acid

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Acids and Bases

• Base a chemical that when dissolved in water
  releases a hydroxide ion (OH-)

XOH (in water) ? OH- X
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Properties of Bases

• Taste bitter cough meds.
• Turn litmus paper back to blue after acid turns
  it red
• Can cause serious burns
• Examples Bleach, KOH, NaOH

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Acids and Bases - Examples

• NaOH H2O ? Na OH- H2O
• HCl H2O ? H Cl- H2O

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Acids and Bases will cancel each other out

• When an Acid and a Base are mixed together they
  will Neutralize each other and create Water and
  a Salt
• This is a Neutralization Reaction

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Neutralization Reaction

• HCl NaOH ? NaCl H2O
• a salt water
• HNO3 KOH ? KNO3 H2O
• a salt water

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Concept of pH

• pH power of Hydrogen
• A way of measuring how many Hydrogen ions, H,
  there are in a solution
• Determines whether a solution is an acid or a base

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pH Scale a measure of the concentration of
Hydrogen Ions
Neutral (water)
Acid
Base
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13
12
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10
9
8
7
6
5
4
3
2
1
0
High H Low OH-
High OH- Low H
H OH-
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Concept of pH

• Where is the safe pH?
• pH must stay between 6.5 - 7.5 in the human body
• Another factor that must maintain homeostasis

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Concept of pH

• Are there exceptions?
• Stomach is acidic
• Intestines are basic
• Buffers are necessary
• weak acids or bases that react with strong acids
  or bases to prevent sudden changes in pH

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What is the pH of Rain water??

• Usually between 5.6- 5.8
• - Water reacts with CO2 in air to form Carbonic
  Acid (H2CO3)

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What is the pH of Rain water??

• Acid Rain
• - Rain water reacts with pollutants such as
  Sulphur dioxide and Nitrogen oxides in air
• - Forms Sulphuric Acid, Nitric Acid, Ammonium
  Sulphate
• - Decreases pH even further