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49 Cards in this Set

  • Front
  • Back
Matter
anything that occupies space and has mass

EX: Rocks , wood, animals, metal, water etc.
Element
a pure substance that can not be broken down into other substances by chemical means.
The basic ingredients of matter
25 Elements that are essential to life
Four of these 25 make up 96% of matter in your body:
Oxygen (65%), Carbon (18.5%), Hydrogen (9.5 %) , Nitrogen (3.3%)
Trace Elements
Make up less than .01 percent of your body but are critical to your health
EX: Iodine: If you don't get 0.15 milligrams your thyroid does not function properly
EX: Iron is essential for carrying oxygen in your blood
A balamced diet will provide most trace elements you need.
Compound
A substance containing two or more elements that are chemically combined IN A FIXED RATIO

EX: H2O Water is always the same ratio of hydrogen and oxygen

Compounds properties vary greatly from the properties of the individual elements that make up the compound
EX: Sodium Chloride: Sodium (Na) is silvery grey metal and Clorine is green gas. Sodium Choloride the compoumd is table salt

Most compoinds found in living organizms are more complex including usually three or four elements.
What are Properties?
Some elements are Solid, some liquid and some gas,
some react with other elements and others hardly react at all
Structure
The components of an atom
Atom
Is the smallest particle of an element

Each element is made up of one type of atom that is different from the atoms that make up each other element
Atoms Structure/Composition
3 Types of Subatomic Particles in an Atom
Made up of subatomic particles
Proton-(Remember "Plus") has a positive + electric charge

Electron-Has a negative electrical charge

Neutron-no electric charge
Protons and Neutrons together make NUCLEUS of an atom
Tightly packed together forming central core called the Nucleus
Electrons
Have LESS MASS THAN than neutrons and protons
Electrons continuously move about the outside of the nucleus at great speed

Electrons negative charge is LIKE A CLOUD around the nucleus/protons and electrons

See picture page 75
An important difference between each element is the number of protons in their atoms

All atoms of one element have the same number of protons The number of protons is also known as the atoms ATOMIC NUMBER

EX: Helium Atom has 2 protons
Helium's atomic number is 2

No two elements have the same atomic number SOOOO no two elements have the exact same chemical behavior

The number of protons determines the atom's properties.
ATOMIC NUMBER
ISOTOPES
An alternate form of an element

Have the same number of protons in their atoms but different numbers of neutrons
EXAMPLE OF ISOTOPE
Three ISOTOPES of carbon
Page 76

Carbon 12
Carbon 13
Carbon 14

There are 6 protons and 6 electrons in each atom but the number of NEUTRONS in each is different
RADIOACTIVE ISOTOPE
One in which the nucleus changes /decays/breaks down over time giving off radiation in the form of matter and energy

Many uses in medical research--can be used as biological spies for observing what happens to different atoms within organizms. Because living cells use radioactive isotopes just as they would use non-radio-active isotopes scientists can detect with instrucemtns the radioactive isotopes .
Electrons in an atom differ in the amount of energy that they have and how tightly they are held by protons in the nucleus
Electrons have different energy levels

Electons in the highest energy level of an atom determine how that atom reacts
How Electrons affect REACTIVITY
p. 77
Lowest Energy Level

Second Energy Level
Is Closest to the nucleus
Can hold two electons

Second level can hold 8 electrons
Reactive?
When energy levels of an atom are only partly filled
This makes them CHEMICALLY REACTIVE
Not Reactive
When there are no PARTIALLY filled energy levels of electrons it is INERT or Not Reactive
CHEMICAL BONDS
join atoms to each other
When outer energy levels are not filled with electrons, different atoms interact, transfer and share electrons.

This process of sharing and transferring electrons creates an attraction or CHEMICAL BOND
CHEMICAL BOND TYPE 1
IONIC BONDS
When an atom transfers an electron to another atom

SEE AND UNDERSTAND PICTURE AT BOTATOM OF PAGE 78
CHEMICAL BOND TYPE 2
COVALENT BONDS
When two atoms share electons
LOOK AT EXAMPLE TOP OF PAGE 79 with DOTS representing electrons
Number of bonds an atom can form
Equals the number of additional electrons that will fill it's highest energy level
Molecule
2 or more atoms held together by covalent bonds

EX: Water molecule H20
3 Kinds of Molecule Models Used in the Book

SEE PAGE 79 Bottom picture
Chemical Formula-Tells you the number and types pf atoms in a molecule

Stuctural formula-Indicates how atoms in a molecule are linked by bonds. Each lline indicates a single covalent bond

Space-Filling Model-Color coded spheres symbolize atoms--a 3 dimensional drawing of a molecule.
CHEMICAL REACTIONS
Chemical changes that result in the formation of one or more substances

EX: Within your cells molecules become re-arranged, chemical bonds break and new ones form--new substances formed Chemical reaction
Chemical Equation
A way to describe what happens when there is a chemical reaction

SEE EXAMPLE PAGE 80
REACTANTS
The starting materials for a chemical reaction
PRODUCTS
The ending material at the end of the chemical reaction
Chemical reactions
Do not create or destroy atoms--only rearrange them.

Rearrangement of them usually involve breaking chemical bonds in reactants and forming new bonds in products.
The STRUCTURE OF WATER
Two hydrogen atoms joined with an oxygen atom by a single covalent bond
Section 4.4
Life depends on the unique properties of water.
All living things are dependent on water
70-95 % of celle are water.
The abundance of water on Earth is one reason it can support life.
Water has extraordinary properties.
Water Molecule
Two hydrogen atoms joined to one Oxygen atom by a single co-valent bond.
Polar Molecule

EX: Water is a polar molecule
A molecule in which the opposite ends have opposite electric charges
Hydrogen Bond
A weak attraction between the hydrogen atom of one molecule and slightly negative atom within another is a type of chemical bond called a hydrogen bond.
Water has Life-Supporting Properties
polar nature of water
effects of hydrogen bonding explain most of water's properties:

cohesion, adhesion, temperature, moderation , lower density of ice compared to liquid water, waters ability to dissolve other substances
Cohesion
The tendancy of molecules that are the same kind to stick to one another

Cohesion in water is much stronger than in other liquids
Adhesion
Attraction between UNLIKE molecules is called adhesion
Cohesion and Adhesion Importance
1.) Effects of cohesion and adhesion is keeping molecules organized and arranged in a way that helps cells function properly

EX: Trees depend on Adhesion and Cohesion==helps water move the right way=resisting the downward pull of gravity so water goes to the top of a tree.
Temperature Moderation
Because of hydrogen bonding, water has a better ability to resist temperature change than most other substances
Thermal Energy
The total amount of energy associated with the movement of atoms and molecules in a sample of matter.
Temperature
is a measure of the average energy of random motion of the particles in a substance. Whjen two substances differ in temperature, thermal energy in the form of heat is transfered from the warmer substance to the cooler one.
When you heat a substance
For example water in a metal pan
molecules of water and of the metal pan move faster and temperature rises because of the molecules

For the WATER some of this thermal energy is absorbed by breaking hydrogen bonds

For the metal pan, there are no hydrogen bonds so all the thermal energy increases the heat

EX: Explains why coastal areas (near water) have less extreme temperatures than inland areas

EX: Water moderates temperature through evaporation--Sweating/Evaporation of Water--As water moleculeds evaporate, the remaining liequid becomes cooler
Low Density of Ice
Density is the amount of matter in a given volume

High density substances are more "packed" than low density substances.

In MOST substances, the solid of a substance is more dense than the liquid form. WATER IS THE OPPOSITE. the Solid form of water ICE , is less dense than water in iliquid form.

WHY? Because water molecules in liquid are moving faster and different hydrogen bonds are breaking --bonds are shorter lived--and liquid molecules fit more closely together than in ice

Substances of lesser density float in substances of greater density:: SOOOO ice floats in water.

If Ice were more dense, it would mean ponds would freeze from the bottom up (ice would sink to the bottom) and fish and plants would freeze /trap them. Instead ice creates an isolation on TOP of the water.
Solution
a uniform mixture of two or more substances

The substance of greater amount in which another substance is dissolved is called the SOLVENT
Solvent
The substance in which another is dissolved. Ex: Dissolve salt in water. There is more water so water is the solvent.
SOLUTE
The substance that is dissolved is the solute. EX above: Salt is the solute.
AQUEOUS SOLUTION
a solution in which WATER is the solvent
WHERE IS WATER THE MAIN SOLVENT?
Inside all cells, in blood and in plant sap.
It dissolves an enormous variety of colutes necessary for life.