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ATOMS (Chapter 4)

Stack #125763

TERMDEFINITION
ISOTOPE This is an atom of an element that has the same number of protons but different number of neutrons
ATOMIC MASS is the average mass of the atoms of an element often expressed in atomic mass units (amu);
VALENCE ELECTRONS the electrons found in the outermost energy level of an atom
ATOMIC NUMBER number of protons in the nucleus of an atom.
MASS NUMBER the sum of the protons and neutrons in the nucleus of an atom (m#=p+n)
PROTONS the positively charged particles found in the nucleus of an atom
NEUTRONS neutrally charged particles found in the nucleus of an atom
ELECTRONS negatively charged particles found in the electron cloud surrounding the nucleus of an atom
11 the mass number is 20, what is the number of neutrons?
CALCIUM What is the name of the element with 20 protons?
NUCLEUS The dense, positively charged center of an atom is called the _
OXYGEN Name this element: there's 2 electrons in 1st shell, 6 in second shell.
Yes, because the number of neutrons differs from # of protons. If an element with atomic # 27 has 26 neutrons, is it an isotope? Explain choice
PHOSPHORUS (atomic #15) Name this element: there's 2 electrons in 1st shell, 8 in second shell, and 5 in last shell.
J. J. THOMSON Which scientist proposed the "plum pudding" model?
ELECTRONS In a single neutral atom the number of protons equals the number of __
ION a charged atom
JJ THOMSON Discovered the electron
E. RUTHERFORD PERFORMED GOLD FOIL EXPERIMENT AND FOUND THAT AN ATOM HAS A POSITIVELY CHARGED NUCLEUS
E. RUTHERFORD His atomic model is nicknamed "nuclear" model
N. Bohr stated that electrons are in specific orbits around nucleus (energy levels)
DEMOCRITUS FIRST TO PROPOSE IDEA OF ATOM; SAID THEY WERE INDIVISIBLE
SCIENTIFIC MODEL A representation of a system or phenomenon; it can be bigger or smaller than what it represents
electron cloud where electrons in an atom are most likely to be found (outside nucleus)
Created by: jsolari