Download The Basics of Atomic Structure

The Basics of Atomic Structure
Terms you should know…
• Atom: smallest unit of an element that
maintains the identity of that element.
• Chemical Reaction: Reaction where atoms
combine in such a way to form new
substances.
Atomic Structure
• Each element has a unique chemical identity.
- The key to understanding the identity of an
atom is in it’s structure and the components
that make up it’s structure.
Atomic Particle Distribution
Subatomic Particles
Electron (e-)
RELATIVE MASS
POSITION
(-) charge
1/1840 amu
located outside
the nucleus
1 amu
Located inside
the nucleus
1 amu
Located inside
the nucleus
Proton (p+)
(+) charge
Neutron (n0)
No charge
What’s amu?
• amu is shorthand for “Atomic Mass Unit (u)”
Atomic Mass Units are the units used to express
atomic and molecular units.
• One atomic mass unit (u) is roughly equal to the
mass of one proton or one neutron. Scientists agreed
to define one amu as 1/12th the mass of a carbon-12
atom. This is the standard by which all other atomic
masses are compared.
• In grams, one atomic mass unit (u) is equal to:
1.66053886 × 10−24 g
Nucleus
• In the center of the
atom and contains the
protons and neutrons
• Makes up 99% of the
mass of the atom.
Elements in the Periodic Table
• Atomic Number:
This is the number of protons
• In a neutral atom:
Number of protons = Number of
electrons
• Mass Number:
Protons + Neutrons (total number of
particles in the nucleus)
• Atomic mass:
the average mass of all known
isotopes of the element
6
C
Carbon
12.001
What is the difference between
mass number and atomic mass
Mass Number
• Protons + neutrons
• Whole number
• Applies to only ONE isotope
• NOT on the periodic table
Atomic Mass
• Weighted average of ALL
isotopes
• Decimal number
• Found on periodic table
So what’s your (atomic) number?
• An element will always have the same number of protons regardless of
the number of neutrons and electrons. An element can be identified by its
Atomic Number.
• Isotopes are atoms with the same number of protons but a different
number of neutrons; therefore, the mass number will be different but the
atomic number will be the same. All atoms of an element are considered
an isotope, some are more common than others.
• An Ion is an element with a number of electrons that differ from its
number of protons. An ion is a charged atom.
– Cation is a positive ion (created when an atom loses electrons)
– Anion is an negative ion (created when an atom gains electrons)
Notice: it’s the number of electrons and neutrons that change, not the
atomic number!
Introduction to Isotopes
• All atoms of an element are considered an isotope, only some
are more common than others.
• Even though isotopes have different amounts of neutrons
they are still chemically alike since they have the same
number of protons and electrons.
• Atomic mass is the average of all isotopes of the element.
Isotope Notation
• Mass number is written
to the top left.
• Atomic number is
written at the bottom
left.
What would the notation
look like for Carbon 14?
So what are isotopes good for?
• Dope testing
- one of the initial tests to determine if
someone has been doping with synthetic
testosterone is a test for a high concentration
of an isotope that’s not contained within
naturally produced testosterone, but within
the synthetic testosterone derived from yams.
More tests will have to be conducted if it is revealed that the athlete is a
vegetarian with an affinity for yams.
Radiometric Dating
Making Bombs