How Atoms Differ. I.Properties of Subatomic Particles ParticleSymbolLocationRelative Charge Relative...
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Transcript of How Atoms Differ. I.Properties of Subatomic Particles ParticleSymbolLocationRelative Charge Relative...
How Atoms Differ
I. Properties of Subatomic Particles
Particle Symbol Location Relative
Charge
Relative mass
Actual mass (g)
Electrone- or In the space
surrounding the nucleus
1-1
1840
9.11
x 10-28
Protonp+ or
In the nucleus 1+ 1
1.673
x 10-24
Neutron
n0 or In the
nucleus 0 11.675
x 10-24
e01
p11
n10
II. Atomic Number• the number of protons in an atom• Identifies element – each atom has unique #– # never changes
III. Mass Number•represents the total number of protons and neutrons in the nucleus
•# of neutrons = mass number – atomic number
IV. Isotopes• Atoms of the same element but have a
different # of neutrons• Ex: 3 isotopes of carbon:
• All elements have isotopes (some 2, some 3, etc.)
• Some isotopes are naturally radioactive.• Ex: Plutonium
V. Representing Isotopes• In Ag-107, the 107 represents the mass number (neutrons + protons)• the 47 represents the number of protons
Practice:
1. What is the mass number for Co-59?2. What is the mass number for
597
VI. Atomic Mass•The standard is the atomic mass unit (amu): defined as 1/12 of the mass of a carbon-12 atom
•the weighted average of the isotopes of that element.•Formula:
Atomic mass of
an element
= (
% abundance
ofIsotope #1
x
massof
Isotope #1
) + (
% abundance
ofIsotope #2
xmass
ofIsotope #2
) + …
Practice 3• Silver has two naturally occurring isotopes. Ag-107 has an abundance of 51.82% and mass of
106.9 amu. Ag-109 has a relative abundance of 48.18% and a
mass of 108.9 amu. Calculate the atomic mass of silver.
Practice 4
• Rubidium is a soft, silvery-white metal that has two common isotopes, Rb and Rb.
If the abundance of 85Rb is 72.2% and the abundance of 87Rb is 27.8%, what is the average atomic mass of rubidium?
8537
8737
Vocabulary to Know
• Atomic #- same # of protons & electrons• Mass #-protons + neutrons
written 2 ways: Carbon-14 or C• Isotopes-same # of protons, different # of
neutrons• Atomic mass-weighted average mass
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