Atomic Structure
Atoms are the building blocks of
matter, and the smallest unit of an
element.
Warm Up
Illustrate and label the following atomic
models:
1.Dalton
2.Thompson
3.Rutherford
4.Bohr
Homework
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4.1 pg 91 1-3
4.2 pg 97 6-8
Pp pg99 11-13
Pp pg 101 14
4.3 pg 104 18-20
4.4 pg 107 23-25
Warm Up
1. Name three things that a block on the periodic
table tells you.
2. Uranium 235 is element 92. How many
neutrons does uranium have?
3. What is an a.m.u.?
4. How much do protons, neutrons and electrons
weigh in a.m.u.’s, respectively?
5. The atomic mass of helium is 4.003. Why?
Warm Up
1.
2.
3.
4.
5.
Define an alpha particle.
Define a beta particle.
Define a gamma particle.
What is radiation?
What is radioactive half-life?
Warm Up
1. What are the 3 parts of an atom and what are the
charges associated with each?
2. Name the following elements: Be, Zr, Ge, Ni, Sc, Y, K,
Na, F and Ne.
3. Give the symbols for the following elements: iron,
magnesium, chromium, gallium, helium, gold, silver,
copper, manganese and mercury.
4. Give the atomic number for the following: hydrogen,
boron, aluminum, titanium, niobium, zinc, molybdenum,
platinum, vanadium and strontium.
Warm Up
1. What is the average atomic mass of the
following: Au, Ag, Ni, C, Na and Cr.
2. How is average atomic mass determined
3. Define the term isotope.
4. How do isotopes relate to average atomic
mass.
5. What are valence electrons?
Warm Up
1. According to the 2n2 rule, what are the maximum
number of electrons that will fit in the 5th orbit of an
atom?
2. According to the 2n2 rule, what are the maximum
number of electrons that will fit in the 6th orbit of an
atom?
3. According to the 2n2 rule, what are the maximum
number of electrons that will fit in the 3rd orbit of an
atom?
4. Draw electron configurations for the following atoms:
Na, Al, P, Ar and Si.
Warm Up
1. The element deuterium has an atomic number of 1 and
has 1 neutron. What is it’s mass, symbol and number
of electrons?
2. Chlorine has a mass of 37 amu’s. What is its symbol,
atomic number and number of neutrons?
3. An unknown element has an atomic number of 12 and
a mass of 25 amu’s. What is it? How many neutrons
does it have?
4. An unknown element has 92 electrons and a mass of
238. What is its name, atomic number and number of
neutrons?
5. Draw an electron configuration for the following
elements: potassium, boron, fluorine and vanadium.
What does the periodic table tell
you about an atom?
• Symbol tells the name of the element. Ex.
(Ne is Neon)
• Atomic number = the # of protons in the
nucleus. (and the number of electrons in a
balanced or neutrally charged atom)
• Average Atomic mass = the weighted
average one atom and its Isotopes.
• Atomic Mass or Mass # = how many
protons and neutrons are in the nucleus.
Inside the center of an Atom
• Nucleus – the dense center of an atom.
• Proton- the positive charged subatomic particle,
located in the nucleus. (determines the atomic
number of an element)
• Neutron- the neutrally charged subatomic
particle in side the nucleus.
• Isotope-an atom who’s # if neutrons is different
or not equal to the number of protons.
• Atoms can exist as many different isotopes. (ex
Carbon-12, Carbon-14)
Outside the nucleus of an atom
• Electron- the negatively charged
subatomic particle of an atom.
• Located in clouds that exist in various
energy levels or shells.
• General rule is n1=2, n2=8, n3=18, n4=32
but there are exceptions. Most typical
exceptions are electron configurations of
transition metals.
Significance of Valence Shells
• Valence Shell- the outer most energy
level. (energy levels increase from the
inside out)
• The # of electrons in the valence shells
determine an atoms ability to react with
other atoms.
• Electrons can be gained or lost from
valence shells, forming ions.
Ions
• Ion-an atom that has gained or lost an electron.
• When an atom loses an electron from its
Valence shell, the result is a positively charged
ion because the # of electrons is less than the #
of electrons.
• When an atom gains an electron in its Valence
shell, the result is a Negative charged ion
because the # of electrons is greater than the #
of protons.
Element
• A substance that cannot be broken down
into smaller substance.
• Elements are arranged in a certain order
based on atomic number on the Periodic
Table.
Periodic Table
helps determine electron arrangement
• Periodic Law states that the chemical and
physical properties of elements change
periodically with the atomic # of elements.
• Periods – a horizontal row of elements.
Indicates how many energy levels the atoms in
that row contain. (how many orbital shells)
• Groups (family)- a vertical column of elements
in the periodic table. Indicates how many
electrons are in the valence shell. ***(The
transition metals are the exception and do have
different numbers of electrons in their valence
shells)
Elements are classified into 3
groups
• Metals – an element that is shiny and
conducts heat and electricity well.
• Metalloids (semiconductors) – conducts
electric current better than a non metal
(insulator), but not as well as a metal
(conductor)
• Non metals – do not conduct heat or
electricity.
Metals
• Alkali metal – any element in Group 1 of
the periodic table.
• Alkaline Earth Metal- any element in
Group 2 of the periodic table.
• Transition Metal – any element in Groups
3-12 of the periodic table.
Alkali Metals
• Found in Group 1
• Have 1 valence electron – this electron can
easily be removed to form a positive ion, and is
the reason elements in this group are highly
reactive with other atoms. (especially elements
in Group 7)
• Are typically soft and shiny
• React violently with water.
• Typically not found in nature as elements
because they are so reative.
Alkaline Earth Metals
• Found in group 2
• Have 2 valence electrons that can be lost,
which causes them to form +2 ions.
• Not as reactive as alkali metals, but still
highly reactive often forming compounds
with atoms of other elements.
• Silvery white in color
• High melting points
• Low densities
Transition Metals
• Found in Groups 3-12
• Have a complex arrangement of electrons.
• Only somewhat reactive, but are still capable. It
takes more energy for transition metals to gain
and lose their valence electrons.
• Can lose up to 4 electrons.
• Are malleable – can be stretched and shaped.
• Are often shiny – or lustrious.
Metalloids - Semiconductor
• Exist in diagonal a diagonal cluster from
group 13 – 17.
• Only 6 elements- boron, silicon,
germaninum, arsenic, antimony, and
tellurium
• Able to conduct heat and electricity under
certain
Non-metals
• Halogens - Group 17
– Very reactive
• Contain 7 electrons in
valence shell.
• Tendency to gain an
electron.
• Like to bond with
Alkali metals.
• Smell bad.
• Noble gases – Group
18, “Inert gases”.
• Exist as single atoms.
• Very rarely form
molecules.
• 8 valence electrons
that saturate the
valence shell. (fill up
to capacity)
Assessment
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Classify the following elements.
a. Iron, Fe
b. Strontium, Sr
c. potassium, d. Platinum, Pt
Predict whether Cesium form Cs+ or Cs- ions.
Predict the charge of a beryllium ion.
Which element is more reactive? Lithium, Li or Beryllium, Be?
Why?
How many neutrons are in the element with atomic #18? Name
this element._________
What is the mass number of this element?____
What family does this element belong to?___ Which Period?___
Is this element very reactive?___ Why?
If this element were to lose 2 electrons, what would be the net
ionic charge?