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ATOMS (Chapter 4)
ATOMIC VOCABULARY
TERM | DEFINITION |
---|---|
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) |