Transcript Development of the Atomic Theory

Atoms and Elements
Notes
Matter
• Anything that has mass and takes up
space
• Made of atoms
Matter
Proton:
Positive & in
the nucleus
Matter
Atom
Anything that
has mass and
takes up
space
Smallest unit
of matter
Neutron:
neutral & in
the nucleus
Electron:
Negative, tiny, &
outside of the
nucleus
ATOMS
• Smallest unit of matter.
– Atoms make up everything
takes up space).
(that has mass and
Protons (+)
• Determines the
identity of the
Element
• Represents the
Atomic #
• Positively charged
• Nucleus
• Part of the atoms
mass
Neutrons – No charge
• Neutral – No charge
• Nucleus
• Part of the atoms
mass
Electrons (-)
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Negatively charged
smallest particles
Outside nucleus
Found in the
electron cloud
• Located in energy
levels
Atomic Particle Size
Nucleus
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Center of the atom
Made up of Protons and Neutrons
Makes up the atoms MASS
Positively Charged!
Electron Cloud
• Area around the
nucleus where
electrons are found.
• Negatively Charged
Energy Levels
• Levels within the electron cloud that
hold a specific # of electrons.
– 1st level - 2 electrons
– 2nd level - up to 8 electrons
– 3rd level – up to 8 or 18
Valence Electrons
• Electrons on the outermost energy level
of the atom.
• Determine the atoms chemical
properties, including reactivity.
Atomic Structure Review
• Protons (+)
– make up the nucleus
• Neutrons
(no charge)
– Make up the nucleus
• Electrons (–)
– Found in energy
levels around the
nucleus in the
electron cloud
Atomic Number
• Top # on the periodic table
• # of protons in the atom
– Atomic # = 2
– 2 protons
Chemical Symbol
• 1 or 2 letter abbreviation for an
element name
– 1st letter Capitalized
– 2nd letter – always lowercase
• Helium - He
Atomic Mass
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Bottom #
Mass of the atom
Located in the nucleus
Equal to Protons + Neutrons
Determining the # of subatomic
particles in atoms
Use the following
A = P = E
M – A = N
Atomic # = Protons = Electrons
Mass – Atomic # = Neutrons
Atom Models
Valence Electrons
• The electrons in the outermost energy
level of the atom.
• What element is this?
• How many valence
electrons does it have?
ELEMENTS
• All the atoms that make up our universe
• Identified by the atomic # (# of protons)
3 Main Groups on the
Periodic Table
Metals
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Make up most of the elements
All solid except Mercury
Has luster (shiny)
Good conductors of heat and electricity
Malleable – hammered or shaped into
thin sheets
• Ductile – stretched into wires
Metals
Nonmetals
• Usually gases or brittle solids
• Poor conductors of heat and electricity
– They are insulators
• Right side of the periodic table
• Only 17 nonmetals
Metalloids
• Called Semi-metals
• Share properties of both metals and
nonmetals
• Located on the zig-zag
line between the metals
and nonmetals.
Groups/Families
• 18 groups
• Vertical Columns on the
periodic table
• Same # of valence
electrons
• Same chemical
properties including
reactivity
• Reactivity – Elements
tendency to undergo
chemical reactions
Periods
• 7 horizontal rows on
the periodic table
• Consist of elements
with the same
number of electron
levels.
Alkali Metals
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Group #1
All metals
1 Valence Electron
Very reactive
Most reactive – the
only need to lose 1
valence electron in
chemical bonds
Alkaline-Earth Metals
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Group #2
All Metals
2 Valence Electrons
Very reactive but
less than group #1.
• Only have to lose 2
valence electrons in
chemical bonds
Valence Electrons
• Group 1 – all elements
have 1 valence electron
• Group 2 – all elements
have 2 valence electrons
Transition Metals
• Groups # 3-12
• All metals
• 1 or 2 valence electrons
• Less reactive than group
#2
• Also contains lanthanide
and actinide series
Groups # 13-16
• Elements change from metals to nonmetals
and include the metalloids.
• Atoms have 10 fewer valence electrons than
the group #.
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Boron Group #13 - 3 valence electrons
Carbon Group #14 - 4 valence electrons
Nitrogen Group #15 - 5 valence electrons
Oxygen Group #16 - 6 valence electrons
Halogens
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Group 17
All nonmetals
7 valence electrons
Very reactive
– Only need to gain 1
more electron for a
total of 8!
Noble Gases/Inert Gases
• Group # 18
• All nonmetals
• 8 valence electrons except helium only
has 2.
• Unreactive
– Have a full outer
electron level
– 2 on the 1st level
– 8 on the 2nd level
Hydrogen stands alone
1 valence electron
Very reactive
Colorless, odorless gas
at room
temperature.
Low density
Reacts explosively
with Oxygen