Atomic Structure
•Anything that has a mass and a volume
•Matter is made up of different kinds
of atoms.
• An _____ is the smallest particle of
an element that has the chemical
properties of the element.
Copper
atoms on
silica
surface.
Distance across = 1.8 nanometer (1.8 x 10-9 m)
• Atoms are the smallest unit of matter
that is still that kind of matter. They
are too small to be seen without very
powerful microscopes.
• Everything is made of atoms
• There are over 100 types of atoms.
• Examples: oxygen, carbon, nitrogen
• Atoms have mass and take up space.
• Atoms are always in motion. The
state of matter of a substance is
determined by how much energy the
atoms have…how much they’re
moving.
• The building blocks of Matter
• Consists of Protons (+), Electrons (-),
and Neutrons (N).
• Consists of only one kind of atom,
• Cannot be broken down into a simpler type of matter
by either physical or chemical means
• Can exist as either atoms or molecules.
Images are from http://www.chem4kids.com
Elements
 Pure substances that cannot be separated into
different substances by ordinary processes
 Are the building blocks of matter
 112 elements known today
Examples:
carbon
gold
calcium
• Elements are made up of all of the same kind of
atom
LecturePLUS Timberlake
7
The Language of Chemistry
• CHEMICAL ELEMENTS
-
– pure substances that cannot be decomposed by
ordinary means to other substances.
Aluminum
Sodium
Bromine
9
Elements
LecturePLUS
Timberlake
Pure substances that cannot be
separated into different substances by
ordinary processes
Are the building blocks of matter
112 elements known today
Examples:
carbon
gold
calcium
• Elements are made up of all of the same kind
of atom
Subatomic Particles
• Proton
• Electron
• Neutron
Protons
• have a positive charge (+)
• found in the nucleus
• have mass
++
++
Neutrons
• have no charge (o)
• found in nucleus
• have mass
o+oo+
o+
Electrons
• have a negative charge (-)
• whirl around nucleus
• have almost no mass o+oo+
o+
-
Subatomic Particles
• Protons and electrons are the only particles that
have a charge.
• Protons and neutrons have essentially the same
mass.
• The mass of an electron is so small we ignore it.
http://www.eskom.co.za/nuclear_energy/fuel/fuel.html
See more diagrams at:
http://www.bmb.psu.edu/courses/bisci004a/chem/basechem.htm
http://www.bmb.psu.edu/courses/bisci004a/chem/atoms.jpg
Draw a diagram showing the
charges of each part of the atom.
ATOM
COMPOSITION
The atom is mostly
empty space
•protons and neutrons in
the nucleus.
•the number of electrons is equal to the number
of protons.
•electrons in space around the nucleus.
•extremely small. One teaspoon of water has 3
times as many atoms as the Atlantic Ocean has
teaspoons of water.
ATOMIC COMPOSITION
• Protons (p+)
– + electrical charge
– relative mass = 1.007 atomic
mass units (amu) but we can round to 1
• Electrons (e-)
–
negative electrical charge
– relative mass = 0.0005 amu
but we can round to 0
• Neutrons (no)
– no electrical charge
– mass = 1.009 amu but we can round to 1
Atomic Number
• is the # of protons in nucleus of
an atom
• it identifies the element
• found above the symbol on the
periodic table
1
H
Hydrogen
1.00
Atomic Mass
• tells the mass of the nucleus
• is the sum of the protons and
neutrons
• found under the symbol on the
periodic table
1
H
Hydrogen
1.00
Electrons
• # of electrons = # of protons in
an uncharged atom
• electron cloud- entire space that
the electrons occupy
Finding # of Neutrons
• Subtract the atomic number from
the rounded atomic mass
Isotopes
• Are atoms of the same element
that have a different number of
neutrons
• These are what cause the atomic
mass to be an average
Atomic Number
All atoms of the same element
have the same number of
protons in the nucleus
13
Atomic number
Al
Chemical symbol
26.981
AVERAGE Atomic Mass
Nucleus
• The nucleus is the center of an atom.
• Made of protons and neutrons.
• The nucleus contains the atom's mass.
Protons
• positively charged particles
• found in the nucleus.
• Have mass = 1.007 atomic mass units
(amu) but we can round to 1
Neutrons
• Uncharged particles
• Found in the nucleus.
• Mass = 1.009 amu but we can round to 1
Electrons
• Negatively charged particles
• Surround the atom's nucleus.
• Chemical reactions involve sharing or
exchanging electrons.
• mass = 0.0005 amu
but we can round to 0
Describe Isotope
Atoms that have the same number
of protons but different numbers
of neutrons
Describe Isotope
Example:
http://education.jlab.org/glossary/isotope.html
Isotopes
• Are atoms of the same element
that have a different number of
neutrons
• These are what cause the atomic
mass to be an average
What is the Electron Cloud Model?
Model of the atom pictures the electrons moving
around the nucleus in a region called an electron
cloud.
The electron cloud is a cloud of varying density
surrounding the nucleus. The varying density
shows where an electron is more or less likely to
be. Atoms with electrons in higher energy levels
have additional electron clouds of different
shapes that also show where those electrons
are likely to be.
For more information, click here:
http://regentsprep.org/Regents/physics/phys05/catomodel/cloud.htm
What is the Electron Cloud Model?
Diagram 1:
What is the Electron Cloud Model?
Diagram 2:
Periodic Table
Atomic number
6
Element’s symbol
C
Element’s name
Atomic mass
Carbon
12.011
Chemical Symbols
• abbreviations for elements
• 1 or 2 letters; 1st is capitalized and
2nd is lower case
• ex-
Aluminum = Al
not AL
Atomic Number
• is the # of protons in nucleus of
an atom
• it identifies the element
• # of protons = # of electrons in
uncharged atom
1
H
Hydrogen
1.00
Atomic Number
All atoms of the same element
have the same number of
protons in the nucleus
13
Al
26.981
Atomic number
Atom symbol
AVERAGE Atomic Mass
Atomic Mass
• tells the mass of the nucleus
• is the sum of the protons and
neutrons
• found under the symbol on the
periodic table
1
H
Hydrogen
1.00
Atomic Mass
• C atom with 6 protons and 6 neutrons
• = 12 atomic mass units
• Mass Number
= # protons + # neutrons
• NOT on the periodic table…(it is the
AVERAGE atomic mass on the table)
• A boron atom can have
5 p + 5 n = 10 amu
10
5
B
Electrons
• # of electrons = # of protons in an
uncharged atom
• electron cloud- entire space that the
electrons occupy
– 1st energy level is full with 2
– 2nd energy level is full with 8
– 3rd energy level is full at 8, but can hold
up to 18 in all the sublevels
Finding # of Neutrons
• Subtract the atomic number from
the rounded atomic mass