Biology Vocab. Ch. 6 - 9th Grade
Terms
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- substance that can't be broken down into simpler chemical substances.
- element
- smallest particle of an element that has the characteristics of that element; basic building block of all matter.
- atom
- the center of an atom
- nucleus
- atoms of the same element that have different numbers of neutrons in the nucleus.
- isotope
- substance composed of atoms of two or more different elements that are chemically combined.
- compound
- chemical bond formed when two atoms combine by sharing electrons.
- covalent bond
- group of atoms held together by covalent bonds; has no overall charge.
- molecule
- atom or group of atoms that gain or lose electrons; has a positive or negative electrical charge.
- ion
- chemical bond formed by the attractive forces between two ions of oppisite charge.
- ionic bond
- all of the chemical reactions that occur within an organism.
- metabolism
- combination of substances in which individual components do not combine chemically and retain their own properties.
- mixture
- mixture in which one or more substances are distributed evenly in another substance.
- solution
- measure of how low acidic or basic a solution is; the scale ranges from 0 to 14; solution with pH or 7 is neutral; above 7, basic, and below 7, acidic.
- pH
- any substance that forms hydrogen ions (H+) in water has a pH below 7.
- acid
- any substance that forms hydroxide ions (OH-) in water and has a pH above 7.
- base
- molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end.
- polar molecule
- weak chemical bond formed by the attraction of positively charged hydrogen atoms to other negatively charged atoms.
- hydrogen bond
- result of diffusion where there is continuous movement of particles but no overall change in concentration.
- dynamic equilirium
- net, random movement of particels from an area of higher concentration to an area of lower concentration, enentually resulting in even distribution.
- diffusion