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Atomic Structure Unit Test Version 1
1- The atomic mass of Magnesium (like most of the atoms) is the weighted average
of the atomic masses of all of the naturally occurring isotopes of Mg.
2- The elements arranged in order of increasing atomic mass are Cl, K, Ar.
3- As the result of the gold foil experiment it was concluded about the structure of an
atom that positively charged nucleus is surrounded by mostly empty space.
4- The subatomic particles found in the nucleus of an atom of Beryllium (like other
atoms) are neutrons and protons.
5- An atom is electrically neutral when the number of protons (positively charged
particles) equals the number of electrons (negatively charged particles).
6- The two notations that represent different isotopes of the same element must have
the same number of protons (atomic number). and are isotopes
of Beryllium because both the notations have the same atomic number 4 (4
protons in the nucleus).
7- The symbol for an atom containing 20 protons and 22 neutrons is 20Ca because
the lower number is the atomic number representing the number of protons and
the top number, the mass number, is the sum of protons and neutrons. The number
of neutron is calculted by subtracting the atomic number (the number of proton)
from the mass number (the sum of protons and neutrons).
8- The atomic mass unit (amu) is defined as exactly
1/12
of
the mass of an atom
of Carbon-12, which can also be written as 6C
9- The charge of an electron and the charge of a proton is described as follow:
An electron has a charge of -1, and a proton has a charge of +1.
4
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