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ATOMICSTRUCTURE Semester Chemistry Unit 2 KNOCKHARDY PUBLISHING.
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Transcript of ATOMICSTRUCTURE Semester Chemistry Unit 2 KNOCKHARDY PUBLISHING.
ATOMICATOMICSTRUCTURESTRUCTURE
Semester Chemistry Unit 2Semester Chemistry Unit 2
KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING
LecturePLUS Timberlake 2
Atomic Theory
Atoms are building blocks of elements
Similar atoms in each element
Different from atoms of other elements
Two or more different atoms bond in simple ratios
to form compounds
THE STRUCTURE OF ATOMSTHE STRUCTURE OF ATOMS
Atoms are the smallest particles of an element that have the properties of that element.
They consist of a number of fundamental particles,the most important are ...
LocationRelative charge
Relative mass (amu)
PROTON Nucleus +1 1
NEUTRON Nucleus 0 1
ELECTRON Electron shells -1 1/1837
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Ions: Atom or electron that has lost or gained electrons.
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Na23
11
Mass Number (A)PROTONS + NEUTRONS
Atomic Number (Z)PROTONS
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Na23
11
Mass Number (A)PROTONS + NEUTRONS
Atomic Number (Z)PROTONS
THESE ALWAYS GO TOGETHER – ANYTHING WITH 11 PROTONS MUST
BE SODIUM
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Na23
11
Mass Number (A)PROTONS + NEUTRONS
Atomic Number (Z)PROTONS
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Na23
11
Mass Number (A)PROTONS + NEUTRONS
Atomic Number (Z)PROTONS
THERE WILL BE 12 NEUTRONS IN THE NUCLEUS
23 – 11 = 12
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Na23
11
Mass Number (A)PROTONS + NEUTRONS
Atomic Number (Z)PROTONS
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Protons Neutrons Electrons ChargeAtomic Number
Mass Number
Symbol
A 19 21 19
B 20 0 40
C + 11 23
D 6 6 0
E 92 0 235
F 6 13
G 16 2- 16
H 27Al3+
MASS NUMBER AND ATOMIC NUMBERMASS NUMBER AND ATOMIC NUMBER
Protons Neutrons Electrons ChargeAtomic Number
Mass Number
Symbol
A 19 21 19 0 19 40 40K
B 20 20 20 0 20 40 40Ca
C 11 12 10 + 11 23 23Na+
D 6 6 6 0 6 12 12C
E 92 143 92 0 92 235 235U
F 6 7 6 0 6 13 13C
G 16 16 18 2- 16 32 32S2-
H 13 14 10 3+ 13 27 27Al3+
RELATIVE MASSESRELATIVE MASSES
Relative Atomic Mass (Ar)The mass of an atom relative to the 12C isotope having a value of 12.000
Ar = average mass per atom of an element x 12 mass of one atom of carbon-12
Relative Isotopic MassSimilar, but uses the mass of an isotope 238U
Relative Molecular Mass (Mr)Similar, but uses the mass of a molecule CO2, N2
Relative Formula MassUsed for any formula of a species or ion NaCl, OH¯
LecturePLUS Timberlake 14
Atomic Mass
• Atomic mass is the weighted average mass of all the atomic masses of the isotopes of that atom.
LecturePLUS Timberlake 15
Example of an Average Atomic Mass
• Cl-35 is about 75.5 % and Cl-37 about 24.5% of natural chlorine.
• 35 x 75.5 = 26.4 • 100• 35.5
35.5 • 37 x 24.5 = 9.07
• 100
ISOTOPESISOTOPES
Definition Atoms with…
the same atomic number but different mass number orthe same number of protons but different numbers of neutrons.
Properties Chemical properties of isotopes are identicalPhysical properties (such as density) can differ
LecturePLUS Timberlake 17
Isotopes
Atoms with the same number of protons, but
different numbers of neutrons.
Atoms of the same element (same atomic
number) with different mass numbers
Isotopes of chlorine
35Cl 37Cl17 17
chlorine - 35 chlorine - 37
LecturePLUS Timberlake 18
Learning Check
• Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms.
• 12C 13C 14C• 6 6 6
• #p _______ _______ _______
• #n _______ _______ _______
• #e _______ _______ _______
LecturePLUS Timberlake 19
Solution
• 12C 13C 14C• 6 6 6
• #p 6 6 6
• #n 6 7 8
• #e 6 6 6
ISOTOPESISOTOPES
Definition Atoms with…
the same atomic number but different mass number orthe same number of protons but different numbers of neutrons.
Properties Chemical properties of isotopes are identicalPhysical properties (such as density) can differ
Theory Atoms of the same element canhave different masses due to thevariation in the number of neutrons inthe nucleus. The atomic mass wasa consequence of the abundance ofeach type of isotope.
Protons Neutrons
1 H 1
1 0
2 H 1
1 1
3 H 1
1 2
ISOTOPES OF HYDROGEN
ISOTOPES - CALCULATIONSISOTOPES - CALCULATIONS
There are two common isotopes of chlorine. Calculate the average relative atomic mass of chlorine atoms
Protons Neutrons %
35 Cl 17
17 18 75
37 Cl 17 17 20 25
ISOTOPES - CALCULATIONSISOTOPES - CALCULATIONS
There are two common isotopes of chlorine. Calculate the average relative atomic mass of chlorine atoms
Method 1 Three out of every four atoms will be chlorine-35
Average = 35 + 35 + 35 + 37 = 35.5 4
Protons Neutrons %
35 Cl 17
17 18 75
37 Cl 17 17 20 25
ISOTOPES - CALCULATIONSISOTOPES - CALCULATIONS
There are two common isotopes of chlorine. Calculate the average relative atomic mass of chlorine atoms
Method 1 Three out of every four atoms will be chlorine-35
Average = 35 + 35 + 35 + 37 = 35.5 4
Method 2 Out of every 100 atoms 75 are 35Cl and 25 are 37Cl
Average = (75 x 35) + (25 x 37) = 35.5 100
Protons Neutrons %
35 Cl 17
17 18 75
37 Cl 17 17 20 25