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anything that occupies space and has mass
all organisms and everything around themcan be found in three physical states:
solid, liquid, gas |
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substance that cannot be broken down into other subtances by chemical reactions
92 naturally occurring elements
ex: carbon, oxygen, gold |
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required in only ver small amounts, but you cannot live without them
Iodine only needed in small amounts but it prevents goiters.
ex: iodine, fluorine |
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two or more elements ina fixed ratio
ex: table salt and water |
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| smallest unit of matter that still retains the properties of an element |
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subatomic particle with a single unit of positive electrical charge
located in the nucleus
mass is very similar to a neutronbut is biggest |
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subatomic particle with a single negative charge
located outside the nucleus and orbits around the nucleus |
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electrically neutral
located in the nucleus
mass is very near the proton but slightly smaller |
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| number of protons in an atom |
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| measure of the amount of material in an object |
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| sum of the number of protons and neutrons in its nucleus |
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forms of an element that differ in mass.
elements that have the same number of protons and electrons, but different numbers of neutrons |
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one in which the nucleus decays spontaneously, giving off particles and energy
Used in PET scanners and used as tracers, monitoring the fate of atoms in living organisms |
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transferring or sharing of outermost electrons between two atoms
ionic, covalent and hydrogen bonds |
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| held together by the attraction between oppositely charged ions by transferring electrons from one atom to another |
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forms when two atoms share one or more pairs of outer-shell electrons
strongest of the various bonds |
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Definition
| unequal sharing of electrons between oxygen and hydrogen atoms forming a polar molecule |
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| atoms or molecules that are electrically charged as a result of gaining or losing electrons |
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| Elements essential to people |
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Definition
Of the 25 elements essential to people... these 4 make up 96% of the weight of most cells.
Carbon
Hydrogen
Nitrogen
The remaining 4% is made up of Calcium, Phosophorus and 14 Trace elements such as:
Iodine
Fluorine |
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| Chemical properties of atoms |
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Definition
| Electrons vary in the amount of energy they possess. The farther they are from the nucleus the greater its energy. |
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| cells constantly rearranging molecules by breaking existing chemical bonds and forming new ones |
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| starting molecules before a chemical reaction |
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| molecules of a chemical reaction that are arranged differently than prior to the chemical reaction |
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tendency ofolecules of the same kind to stick together
much stronger for water than for most other liquids |
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| the amount of energy associated with the movement of atoms and molecules in a body of matter |
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| measures the intensity of heat, the average speed of molecules |
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Cohesive nature of water
Ability of water to moderate temperature
Biological significance of ice floating
Versatility of water as a solvent |
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| tendency of molecules of the same kind to stick together |
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| measure of how difficult it is to stretch or break the surface of a liquid |
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| surface of liquid remaining cooling after a substance evaporate (hottest ones vaporize first) |
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| liquid consisting of a homogenous mixture of two or more substances |
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| any substance that is dissolved |
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| when water is used as the solvent |
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| chemical compound that releases H+ to a solution |
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| compound that accepts H+ and removes them from solution |
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| measure of hydrogen ion (H+) concentration in a solution |
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| contained in biological fluid and minimizes changesin pH by accepting H+ when that ion is in excess and donating H+ when it is depleted |
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| Positive and negative poles cause adjacent water molecules to become attracted to each other. ALL properties of water arise from this atomic stickiness |
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| Van der Waals interactions |
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Definition
| attractions between molecules that are close together due to electrons being distributed assymetrically in molecules or atoms, resulting in "hot spots" of negative or positive charge |
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