Transcript atoms - Decatur ISD

ATOMS
• Basic building blocks of matter.
– Atoms make up everything
takes up space).
(that has mass and
Atomic Structure
• Protons – positively
charged particles inside
the nucleus.
• Neutrons – neutral
particles inside the
nucleus that have No
charge.
• Electrons – negatively
charged particles in
atoms found around the
nucleus.
A = P = E
M – A = N
• Atomic # = Protons = Electrons
• Mass – Atomic # = Neutrons
Atomic Particle Size
Atomic Mass Unit - amu
• Unit of measurement for the mass of
subatomic particles.
– 1 amu = 1.7 X 10 -24 They are TINY!!!
• .000000000000000000000017 grams
– Proton = 1 amu
– Neutrons = 1 amu
– Electrons = almost zero (TINIEST particle with
the least mass)
– Most mass is in the nucleus with protons and
neutrons
– Otherwise atoms are mostly EMPTY SPACE
Atomic Number
• The number of protons inside the
nucleus of the atom.
• Determines the element.
• Atoms have no charge because the # of
protons (+ charge) is = to the # of
electrons (- charge).
Mass
Number/Atomic
Mass
• The total number of protons and
neutrons in an atoms nucleus.
• Protons + Neutrons = Mass Number
• Notice how massive the nucleus is
compared to the rest of the atom
Atomic Mass
• The weighted average of the masses of
all the naturally occurring isotopes of an
element.
• Average of Protons + Neutrons of all an
elements Isotopes = Atomic Mass
Electron Cloud
• Area around the nucleus where electrons are
arranged.
• 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
• The electrons in the outermost energy
level (electron cloud).
• 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 – made into different shapes
Ductile – made into wires
Metals
Nonmetals
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Usually gases or brittle solids
Poor conductors of heat and electricity
Right side of the periodic table
Only 17 nonmetals
Metalloids
• Called Semi-metals
• Share properties of both metals and
nonmetals
Groups/Families
• Columns of the periodic
table
• Each element has the
same # of valence
electrons
• The elements share
similar chemical and
physical properties.
• They are each part of
the same “family”
Periods
• 7 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