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49 Cards in this Set
- Front
- Back
Matter
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anything that occupies space and has mass
EX: Rocks , wood, animals, metal, water etc. |
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Element
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a pure substance that can not be broken down into other substances by chemical means.
The basic ingredients of matter |
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25 Elements that are essential to life
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Four of these 25 make up 96% of matter in your body:
Oxygen (65%), Carbon (18.5%), Hydrogen (9.5 %) , Nitrogen (3.3%) |
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Trace Elements
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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. |
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Compound
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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. |
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What are Properties?
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Some elements are Solid, some liquid and some gas,
some react with other elements and others hardly react at all |
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Structure
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The components of an atom
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Atom
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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 |
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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 |
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Protons and Neutrons together make NUCLEUS of an atom
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Tightly packed together forming central core called the Nucleus
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Electrons
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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 |
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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
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ISOTOPES
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An alternate form of an element
Have the same number of protons in their atoms but different numbers of neutrons |
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EXAMPLE OF ISOTOPE
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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 |
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RADIOACTIVE ISOTOPE
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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 . |
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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
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p. 77
Lowest Energy Level Second Energy Level |
Is Closest to the nucleus
Can hold two electons Second level can hold 8 electrons |
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Reactive?
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When energy levels of an atom are only partly filled
This makes them CHEMICALLY REACTIVE |
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Not Reactive
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When there are no PARTIALLY filled energy levels of electrons it is INERT or Not Reactive
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CHEMICAL BONDS
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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 |
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CHEMICAL BOND TYPE 1
IONIC BONDS |
When an atom transfers an electron to another atom
SEE AND UNDERSTAND PICTURE AT BOTATOM OF PAGE 78 |
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CHEMICAL BOND TYPE 2
COVALENT BONDS |
When two atoms share electons
LOOK AT EXAMPLE TOP OF PAGE 79 with DOTS representing electrons |
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Number of bonds an atom can form
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Equals the number of additional electrons that will fill it's highest energy level
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Molecule
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2 or more atoms held together by covalent bonds
EX: Water molecule H20 |
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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. |
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CHEMICAL REACTIONS
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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 |
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Chemical Equation
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A way to describe what happens when there is a chemical reaction
SEE EXAMPLE PAGE 80 |
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REACTANTS
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The starting materials for a chemical reaction
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PRODUCTS
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The ending material at the end of the chemical reaction
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Chemical reactions
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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. |
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The STRUCTURE OF WATER
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Two hydrogen atoms joined with an oxygen atom by a single covalent bond
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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. |
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Water Molecule
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Two hydrogen atoms joined to one Oxygen atom by a single co-valent bond.
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Polar Molecule
EX: Water is a polar molecule |
A molecule in which the opposite ends have opposite electric charges
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Hydrogen Bond
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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.
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Water has Life-Supporting Properties
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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 |
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Cohesion
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The tendancy of molecules that are the same kind to stick to one another
Cohesion in water is much stronger than in other liquids |
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Adhesion
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Attraction between UNLIKE molecules is called adhesion
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Cohesion and Adhesion Importance
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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. |
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Temperature Moderation
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Because of hydrogen bonding, water has a better ability to resist temperature change than most other substances
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Thermal Energy
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The total amount of energy associated with the movement of atoms and molecules in a sample of matter.
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Temperature
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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.
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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 |
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Low Density of Ice
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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. |
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Solution
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a uniform mixture of two or more substances
The substance of greater amount in which another substance is dissolved is called the SOLVENT |
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Solvent
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The substance in which another is dissolved. Ex: Dissolve salt in water. There is more water so water is the solvent.
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SOLUTE
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The substance that is dissolved is the solute. EX above: Salt is the solute.
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AQUEOUS SOLUTION
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a solution in which WATER is the solvent
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WHERE IS WATER THE MAIN SOLVENT?
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Inside all cells, in blood and in plant sap.
It dissolves an enormous variety of colutes necessary for life. |