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Definition of A, Z and isotopes
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The periodic table is arranged in order of increasing atomic
number
Number of protons in an atom
Z
An individual atom is
electrically neutral
An individual atom is
electrically neutral
How manyHow many protonsprotons andand electronselectrons
are in anare in an oxygen atom?oxygen atom?
How manyHow many protonsprotons andand electronselectrons
are in anare in an oxygen atom?oxygen atom?
protonsprotons = 88electronselectrons = 8
protonsprotons = 9292electronselectrons = 92
Total numberTotal number of of protons protons andand
neutronsneutrons in an atom of a given in an atom of a given
isotope isotope
Mass NumberMass Number
Mass number is the number of protons and neutrons in the nucleus of an isotope.
Nuclide p+ n0 e- Mass #
Oxygen - 10
- 33 42
- 31 15
8 8 1818
Arsenic 75 33 75
Phosphorus 15 3116
A = 12
A = 238
A xz
Mass #
At. #
Write the symbol for the atom Write the symbol for the atom
that has anthat has an atomic number of 9 and aand a mass
number of 19.
19F9
How many electrons and how
many neutrons does the atom
have?
How many electrons and how
many neutrons does the atom
have?
19F99
How many electrons and how many neutrons
does the atom have?
How many electrons and how many neutrons
does the atom have?
19F99
number of neutrons = mass # - at. #
# of neutrons = A- Z
A= 19
Z = 9
# of neutrons = 19 - 9
= 10 neutrons = 10 neutrons
31X15
173X7070
Identify the element
66 protons protons
6 neutrons
9292 protonsprotons
146146 neutronsneutrons
All atoms of the same element do not necessarily have the same
number of neutrons in their nuclei
Atoms of the Atoms of the samesame
elementelement that have that have different numberdifferent number of of
neutronsneutrons
Atoms of the Atoms of the samesame
elementelement that have that have different numberdifferent number of of
neutronsneutrons
Isotopes…Again Isotopes…Again (must be on the test)(must be on the test)
Isotopes are atoms of the same element having different masses due to varying numbers of neutrons.
Isotope Protons Electrons Neutrons Nucleus
Hydrogen–1
(protium)
1 1 0
Hydrogen-2
(deuterium)
1 1 1
Hydrogen-3
(tritium)
1 1 2
When an atom losesloses or gains an electron
More More protonsprotons than than
electronselectrons
positive charge positive charge ++
CATION
More More electronselectrons than than protonsprotons
negative negative charge charge --
ANION
How many p+, e- and neutrons are
present in the following atom or ion?
24 Mg12
24 Mg12
MgMg atomatom – – neutral neutral 12 p+, 12 e-12 p+, 12 e-
If it loses 2e- ??? If it loses 2e- ??? What is it’s What is it’s
charge?charge?# of p+ = +12# of p+ = +12# of e- = -10# of e- = -10
+ 2
24 Mg 2+
12
Magnesium
cation
Write the chemical symbol for the ion with 9 protons
and 10 electrons
19F
-19
# of neutrons = 27 - 13 = 14
27Al
+3
Write the chemical symbol for the ion
with 7 protons and 10 electrons
14N-3
7
How many protons and electrons are present in
the S-2 ion?
32S-21616
Metal Initial Appearance
MetalCu(NO3)2
Cu+2 Mg(NO3)2 Mg+2 Zn(NO3)Zn+2 AgNO3 Ag+
Cu
Mg
Zn
Initial Appearance of Each Metal
Metal Reactivity
