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49 Cards in this Set
- Front
- Back
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What is matter?
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- anything that occupies space and has mass
- found in 3 states; solid, liquid, gas |
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What is an element?
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substance that can't be broken down to other substances by ordinary chemical means
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What is a compound?
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substance consisting of 2 or more elements combined in a fixed ratio
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What 4 elements make up 96% of the human body?
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- Oxygen
- Carbon - Nitrogen - Hydrogen |
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What are trace elements?
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- essential, but only in minute quantities
EX: iron |
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What is an atom?
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smallest unit of matter that still retains the properties of an element.
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What is a proton?
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subatomic particle with a single positive electrical charge.
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What is an electron?
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subatomic particle with a single negative charge
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What is a neutral charge?
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- electrically neutral
- has no charge |
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What is a nucleus?
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- atom's central core, containing protons and neutrons
- genetic control center of a Eukaryotic cell |
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What is an atomic number?
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number of protons in each atom of a particular element
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What is a mass number?
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sum of the number of protons and neutrons in its nucleus
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What is atomic mass?
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- total mass of an atom
- aka atomic weight - given as a whole number - approximately = the mass number |
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What is an isotope?
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1 of several atomic forms of an element, each with the same number of protons but a different number of neutrons
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What is a radioactive isotope?
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isotope n which the nucleus decays spontaneously, giving off particles and energy
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organisms incorporate radioactive isotopes of an element into their molecules, and researchers can use special scanning devices to detect the presence of those isotopes in biological pathways or locations in the body
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Why are radioactive isotopes useful as tracers in research on the chemistry of life?
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Of the 3 subatomic particles which is involved directly in chemical activity of an atom?
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electron
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What are electron shells?
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energy level representing the distance of an electron from the nucleus of an atom
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What is a chemical bond?
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- attraction between 2 atoms resulting from a sharing of outer-shell electrons or presence of opposite charges on the atoms
- bonded atoms gain complete outer shells |
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What is covalent bonds?
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- strongest kind of chemical bond in which 2 atoms share 1 or more pairs of outer-shell electrons
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What is a molecule?
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2 or more atoms held together by covalent bonds
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What is electronegativity?
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attraction of a given atom for the electrons of a covalent bonds
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What are nonpolar covalent bonds?
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covalent bond in which electrons are shared equally between 2 atoms of similar electronegativity
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What are polar covalent bonds?
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- covalent bond between atoms that differ in electronegativity.
- shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive. |
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What is a polar molecule?
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molecule containing polar covalent bonds and having an unequal distribution of charges
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What is an ion?
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atom or molecule with an electrical charge resulting from a gain or loss of 1 or more electrons
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What is an ionic bond?
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chemical bond resulting from the attraction between oppositely charged ions.
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What is salt?
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- compound resulting form the formation of ionic bonds
- aka ionic compounds |
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What is a hydrogen bond?
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type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in 1 molecules is attracted to the partially negative atom participating in a polar covalent bond in another molecule
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What is a chemical reaction?
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breaking and making of chemical bonds, leading to change in the composition of matter.
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What are reactants?
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starting materials in a chemical reaction
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What is a product?
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material resulting from the chemical reaction
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What is cohesion?
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tendency of molecules of the same kind to stick together
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what is adhesion?
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clinging of 1 substance to another
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What is surface tension?
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measure of how difficult it is to break or stretch the surface of a liquid.
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What is heat?
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amount of energy associated with movement of atoms and molecules in a body of water
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What is temperature?
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- intensity of heat
- average speed of molecules rather than the total amount of heat energy in a body of water |
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What is evaporative cooling?
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process in which the surface of an object becomes cooler during evaporation
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water in the crevices of a boulder expands as it freezes because the water molecules become spaced further apart in forming ice crystals, cracking the rock.
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How does the freezing of water crack a boulder?
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What is a solution?
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liquid consisting of a uniform mixture of 2 or more substances
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What is a solvent?
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dissolving agent
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What is a solute?
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substance that is dissolved
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What is an aqueous solution?
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solution where water is the solvent
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What is an acid?
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compound that donates hydrogen ions to solutions
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What is base?
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compound that accepts hydrogen ions and removes them from solution
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What is pH scale?
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- describes how acidic or basic a solution is
- ranges from 0 (most acidic) to 14 (most basic) |
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What is a buffer?
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substance that minimize change in pH.
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What is acid precipitation?
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refers to rain, snow, or fog with a pH lower than 5.2
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What is ocean acidification?
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decreasing pH of ocean water due to absorption of excess atmospheric CO2 from the burning of fossil fuels.
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