atom basics
TRANSCRIPT
LecturePLUS Timberlake 1
The AtomAtomic Number and Mass
NumberIsotopes
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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
LecturePLUS Timberlake 3
Subatomic Particles
Particle Symbol Charge RelativeMass
Electron e- 1- 0
Proton p+ + 1
Neutron n 0 1
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Location of Subatomic Particles
10-13 cm electrons
protons neutrons
10-8 cm
nucleus
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Atomic Number
Counts the number of
protonsin an atom
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Periodic Table
Represents physical and chemical behavior of elements
Arranges elements by increasing atomic number
Repeats similar properties in columns known as chemical families or groups
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Periodic Table
1 2 3 4 5 6 7 8
11 Na
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Atomic Number on the Periodic Table
11Na
Atomic Number
Symbol
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All atoms of an element have the same number of protons
11Na
11 protons
Sodium
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Learning Check AT 1
State the number of protons for atoms of each of the following:A. Nitrogen 1) 5 protons 2) 7 protons 3) 14 protons
B. Sulfur 1) 32 protons 2) 16 protons 3) 6 protons
C. Barium1) 137 protons 2) 81 protons 3) 56 protons
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Solution AT 1
State the number of protons for atoms of each of the following:A. Nitrogen 2) 7 protons B. Sulfur
2) 16 protons
C. Barium3) 56 protons
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Number of Electrons
An atom is neutral The net charge is zeroNumber of protons = Number of electronsAtomic number = Number of electrons
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Mass Number
Counts the number of
protons and neutronsin an atom
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Atomic Symbols
Show the mass number and atomic number
Give the symbol of the element
mass number 23 Na sodium-23
atomic number 11
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More Atomic Symbols
16 31 65 O P Zn 8 15 30
8 p+ 15 p+ 30 p+
8 n 16 n 35 n8 e- 15 e- 30 e-
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Masses of AtomsA scale designed for atoms gives their small
atomic masses in atomic mass units (amu)An atom of 12C was assigned an exact mass of
12.00 amuRelative masses of all other atoms was
determined by comparing each to the mass of 12C
An atom twice as heavy has a mass of 24.00 amu. An atom half as heavy is 6.00 amu.
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Atomic Mass
Listed on the periodic tableGives the mass of “average” atom of each
element compared to 12C Average atom based on all the isotopes and their
abundance %Atomic mass is not a whole number
Na22.99
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Learning Check AT6
Using the periodic table, specify the atomic mass of each element (round to the tenths place): A. calcium __________B. aluminum __________C. lead __________D. barium __________E. iron __________
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Solution AT6
Using the periodic table, specify the atomic mass of each element (round to the tenths place):A. calcium _40.1 amu _ B. aluminum _27.0 amu _ C. lead _207.2 amu_D. barium _137.3 amu_E. iron _55.8 amu__