SCIENCE TEST TOMORROW Flashcards
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simplest pure substance that can’t be broken down
Element
a pure substance made of two or more elements that are chemically combined
Compound
two or more substances that are in the same place but not chemically combined
Mixture
What are the three subatomic particles?
Protons, neutrons, and electrons
Where are they found and located?
Protons- positive charge; inside
Neutrons- neutral (neutral charge); inside (carries the weight)
Electrons- negative; outside
Summarize atomic theory:
positive charge centered in nucleus
Rutherford
atoms can only be rearranged because they cannot be created or destroyed
elements are made of atoms that cannot be divided
a compound is composed of atoms of different elements that are combined in a specific ratio
Dalton
atoms contain a negative and a positive charge-
Thompson
electrons move in specific orbits
Bohr
How many valence electrons are needed for an element to be stable?
8 valence electrons (except helium which is stable with 2)
How is the periodic table organized?
Increasing atomic number
How are the elements arranged?
periods and groups; groups are organized by valence electrons
can you identify the number of protons, neutrons, electrons, and atomic mass of an element?
Protons: atomic number
Neutrons: mass - atomic number
Electrons: atomic number
Can you identify if an element is an isotope?
Yes – different # of neutrons
anything that has mass and occupies space
matter
