how atoms differ. i.properties of subatomic particles particlesymbollocationrelative charge relative...
TRANSCRIPT
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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