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34 terms

8th Grade Science Notes: Chemistry

Overall Chemistry Vocabulary; Key Points
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Element
simplest pure substance
Atoms
the basic building blocks of all matter.
Atoms (made of)
made of protons, neutrons, and electrons.
Protons
POSITIVELY charged and inside the nucleus
Neutrons
NEUTRAL particles inside the nucleus
Electrons
NEGATIVELY charged particles OUTSIDE the nucleus
Atomic Number
determines an elements identity and the number of protons and electrons in an atom.
Atomic Mass
protons + neutrons
A.P.E.
Atomic #= # of protons= # of electrons
M.A.N.
Mass-Atomic#=#of neutrons
Alkali Metals
Extremely reactive, containing one valence electron, and is never found in their pure form.
Alkaline-Earth Metals
Slightly less reactive than Alkali Metals, and have 2 valence electrons.
Transition Metals
Shiny, less reactive, and good conductors
Lanthanides and Actinides.
Transition metals that are reactive
Lanthanides
Shiny & reactive
Actinides
Radio active
Period
tells the number of electron shells
group
# of valence electrons
Halogens
very reactive non metals that are poor conductors and tend to go with Alkali metals
Noble Gases
non reactive non metals
Isotopes
Atoms of elements that have the same number of protons but a different number of neutrons inside the nucleus
Ions
Charged particles that form during chemical changes. They form when one or more valence electron is transferred.
Subscript
tiny numbers to the bottom right of an element's symbol
Coefficent
a number placed in front of a molecular formal to indicate how many molecules/atoms take part in the reaction.
Chemical reaction
Chemical changes
Chemical change
Tigers Pounce on colored Geckos
Law of Conservation of mass
in a chemical change, the mass of reactants at the start is equal to the mass of the products
reactant
any substance that is used up during a reaction
product
any substance that is produced during a reaction
Physical Properties
easily observed w/o tempering with the product
Chemical Properties
only observed during chemical reactions. ex) is it combustable?
Physical changes
occur when substances are changed to another phase, are separated or combined. No new substance is produced
Phase Changes
ex) Melting=solid>liquid
chemical changes
occur when a new chemical substance is produced after a reaction