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Elements
Question | Answer |
---|---|
Atomic symbol | shorthand method for indication the name of an element |
Atom | the smallest paricle of an element that remains the elements properties |
Nucleaus | positively charged center of the atom |
Proton | particles in the nucleaus with a charge of +1 |
Neutron | particles in the nucleaus with no charge |
Electron | paricles around the nucelaus with a charge of -1 |
Democritus | Greek philosopher around 400 B.C who propsed the ides that atoms make up all matter |
Aristotle | Greek philospher who disputed Democritus idea and proposed matter whas uniform throughout and made of 5 elements |
Thomson model | thomson discovered the electron and proposed that electron floated around in atoms like plums in plum pudding |
Rutherford model | Rutherford proposed that all the positive charge of an atom was concetrated in the nuclues and was surrounded by electrons with empty space in between |
Bohr model | Bohr proposed that electrons travel in fixed orbits like planets orbiting the sun |
electron cloud model | present model in which electrons travel in unpredictable paths around the nuclues |
Atomic number | the number of protons in an atoms nucleus |
Mass number | sum of the number of protons and neutrons in the nucleus of an atom |
Isotopes | atoms of the same element that have different numbers of neutrons |
Half-life | amount it takes for half of a sample of an isotpe to break down into other elements |
Carbon dating | using the decay of C-14 to determine the age of organic substances |
Average atomic mass | the weighted average mass of all naturally occuring isotopes of an element |
Valence electrons | electrons in the outermost sublevel of an atom |
Dmitri Mendeleev | Develped first periodic table in late 1800s |
Henery G.J Mosely | Developed the modern perodic table in 1913 |
Groups | vertical colums on perodic table |
Electric dot diagram | the symbol of an element surrounded by dots to represent valence electrons |
Periods | rows on the perodic table |
Ductile | can be drawn into wires |
Malleable | easily bend or pounded into sheets |
Metalloids | elements along the stair step line of the perodic table that have properties that lie somwhere between metals and nonmetals |
Diatomic elements | elements in which tow atoms of the same element are almost alway bonded together |