THE PERIODIC TABLE
1869
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1914
Dmitri Mendeleev – invented the periodic table
Made the first periodic table by arranging all known elements by atomic weight, chemical and physical
characteristics/properties and left blank spaces where he thought elements were missing
When he put the elements in groups according to their chemical and physical properties, he found a repeating
pattern - he called an octet
His table was the start, but had some mistakes
Henry Mosely – improved Mendeleev’s table
 Used x-rays to count the number of protons in an atom
 Found that different elements have different numbers of protons
 Changed the periodic table by arranging his table by number of protons – atomic number instead of
atomic weight, and chemical and physical properties
THE MODERN PERIODIC TABLE – is arranged by increasing atomic number (the number of protons)
PERIODIC TABLE
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Atomic Number = the number of Protons
Atomic Mass = the total number of particles (protons and neutrons) in the nucleus
Chemical Symbol = the abbreviation for the element name
*NOTE: many element names are LATIN
GROUP OR FAMILY = the vertical columns on the table
Elements in the same group/family are similar
There are 10 families –including Hydrogen as its own family
Family/Group
Family Elements
#1 Alkali Metals
#2 Alkaline Earth Metals
Hydrogen,Lithium, Sodium
Magnesium, calcium,
radium
Gold, Silver, Iron
Boron, Aluminum, Gallium
Carbon, Silicon, Tin
Nitrogen, Phosphorus,
Arsenic
Oxygen, Sulfur, Selenium
Fluorine, Chlorine,
Bromine
Helium, Neon, Argon
Hydrogen
#3 Transition Metals
#4 Boron Family
#5 Carbon Famil
#6 Nitrogen Family
#7 Oxygen Family
#8 Halogens
#9 Noble Gases
#10 Hydrogen
Outer Level Electrons
Reactivity
1
Most reactive metal
2
1, 2, or 3
3
4
Highly reactive
Less reactive
Less reactive
Somewhat reactive
5
6
Somewhat reactive
Very reactive
7
8
1
Most reactive non-metal
INERT – non-reactive
Reactive
NOTE: The periodic table is arranged in vertical columns (called families or groups) with metals on the left,
metalloids further right and non-metals on the far right…the table is made up mostly of metals
NOTE* Members of the same group have similar physical and chemical properties, so we sometimes call these
groups families
NOTE: Chemical reactions are all about the ELECTRONS
NUMBER 8 is the magic number! All elements want to be STABLE and having 8 electrons on their
outer level makes them STABLE. Recall that atoms have the same number of protons and electrons. In
chemical reactions, atoms gain or lose electrons in order to be STABLE with 8 on their outer level.
When this happens, they will have different numbers of electrons. Gaining or losing electrons will
turn the once neutral atom into an ION – which is an atom that is no longer neutral
Question WHY DO ELEMENTS REACT?
Answer - Its all about the ELECTRONS
Sodium has 11 protons and 11 electrons
2 on the K shell, 8 on the L shell, and 1 on the outer shell – its will readily react giving up its 1 OLE
Argon has 18 protons and 18 electrons
2 on the K shell, 8 on the L shell, and 8 on the outer shell – it will NOT react; Its last level is FULL at 8
Neon has 10 protons and 10 electrons
2 on the K shell, and 8 on the outer shell – Outer level is full, Will NOT react
Chlorine has 17 protons and 17 electrons
2 on the K shell, 8 on the L shell, and 7 on the outer shell – it will readily react by taking an electron in order to
Have a full outer shell …see Sodium above. It has one OLE so Chlorine will take Sodium’s electron in order to
be stable. Chlorine had 7 OLE and needed 1 to have 8, so it will take chlorine’s 1 OLE
SHELLS
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Electrons- Travel around the nucleus in orbitals or shells
The first shell – K shell – holds 2 electrons…then it is full
The second shell – L shell - holds 8 electrons until full
The third shell - M shell – holds 8 electron until full
The fourth shell - N shell – holds 18 electrons until full
The fifth shell -O shell – holds 18 electron until full
The sixth shell – P shell – holds 32 electrons until full
The seventh shell – Q shell – holds 32 electrons until full
Bigger shells (n-o-p-q) are actually made up of smaller shells called sub-orbitals
The outer shell is full at 8 electrons
In the transition metals, most of the electrons go into the sub-orbitals leaving only 1, 2, or 3 electrons on the
last or outer shell
NOTE: Group number tells us how many electrons are on the last shell
Ex. Alkali Metals are all in group 1 and all have 1 OLE (outer level electron)
Alkaline Earth Metals are all in group 2 and all have 2 OLE
Transition Metals (groups 3 – 12) all have 1, 2, or 3 OLE
Boron Family (group 13) have 3 OLE
Carbon Family (group 14) have 4 OLE
Nitrogen family (group 15) all have 5 OLE
Oxygen family (group 16) all have 6 OLE
Halogens (group 17) all have 7 OLE
Noble Gases (group 18) all have 8 OLE
NOTE: All elements react except Noble Gases…they all have exactly 8 OLE and are STABLE.
All other elements are noble gas wannabees – nature loves stability and all want to be stable
So all other atoms want to be STABLE…like the noble gases…with 8 outer level electrons.
VALENCE
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The charge of an atom after it gives or takes electrons
The number of electrons an atom will gain or lose in order to have a full shell (8 electrons)
All shells are considered full with 8 electrons
Atoms will gain or lose electrons – whichever is easier – to have exactly 8 electrons on it outermost
level
Example: Sodium (Na) has 11 protons, 11 electrons – 2 on the first level, 8 on the second level and
1 electron on its outer level. It wants 8. Which is easier…to gain 7 or lose 1? Answer”
It is easier to lose one…so when that happens it will have 11 p It is no longer neutral.
It now has one less electron that number of protons. That means it is in a sense – less
negative. Since it gave up 1 electron, (and became more positive) it now has a valence
of +1 (that 1 is the number of electrons it lost)
ION - an atom that is no longer neutral
Example: Calcium (Ca) has 12 electrons (and 12 protons) Remember! The protons determine what the
Element is. Calcium has 2 electrons on the first shell, the second shell is full with 8, the third shell is
Calcium’s outer shell and it has 2 electrons on it. REMEMBER! It wants 8. S0…it will LOSE 2
(which is easier that gaining 6) because it wants 8 on its outer level. Since it got rid of 2 electrons, it
became less negative and now has 12 protons, but only 10 electrons. It is no longer a neutral atom It
has become an ION with a valence of +2
Example: Chlorine has 17 protons and 17 electrons.
Shell one has 2 electrons and is full. Shell 2 has 8 and is full. Shell 3 can hold 8, but there are only
7 electrons left. So chlorine wants to be full with 8…it will be easier to GAIN 1 electron that to lose
7 electrons. So Chlorine will look to GAIN 1 electron to make it stable with 8. It is no longer neutral.
It now has 17 protons and 18 electrons. Since it gained an electron to make it more stable, it has
Become more negative and is no longer an atom. It is now an ion with a valence of -1
RE – CAP
 Elements will give or take electrons to have a full outer shell
 Valence – tells how many electrons the element will give or take
THE PERIODIC TABLE IS MADE UP OF METALS, NON-METALS AND
METALLOIDS
1.
METALS –
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Located left side of the table
Usually 3 or fewer electrons in the last shell
Shiny
Good conductors of heat and electricity
Solids at room temp…EXXCEPT…mercury (Hg)
Malleable and ductile
All have a valence of +1, +2, or +3
NOTE: Metals all have a positive valence
Metals are ELECTRON GIVERS
2.
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NON-METALS
Located on right side of the table
Usually 5 or more electrons in the last shell
Not shiny
Poor conductors of heat and electricity
Good insulators
Solids and gases at room temp…EXCEPT…Bromine
Brittle
All have negative valences
Non-Metals are all ELECTRON TAKERS
3.
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METALLOIDS
Located along the zigzag line on the table
Usually 3 – 6 electrons in the last shell
Some shiny - some dull
Some are poor conductors of heat and electricity - some are conductors
They are solids at room temp
Some are brittle
Their properties can change with temp
Metalloids are great for use in electronic device
VOCABULARY TERMS TO KNOW
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Equation
Formula
Reactants
Products
Element
Compound
Valence
Ion
Bond
Atomic Number
Atomic mass
Chemical Symbol
Periodic Table
Full level
Metals
Non-Metals
Chemical Equation
Isotope
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Inert
a method of showing what happens in a chemical reaction
the elements present in a compound
the elements that react together in a chemical reaction (on the right)
what is formed in a chemical reaction (on the left)
a pure substance that cannot be broken down into simpler substances
two or more different elements that combine
the number of electrons an element gives or takes in a chemical reaction
an atom that is no longer neutral
an invisible force that causes elements to join together in a chemical reaction
the number of protons in an element
the total number of particle (protons and neutrons) in the nucleus
the abbreviation for the element name (many in Latin)
made up of metals, metalloids, non-metals (mostly metals)
all shells are considered full with 8 outer level electrons
metals give electrons
take electrons
made up of the reactants (on the right side of the =) and the products on the left
atoms of the same element with different numbers of neutrons and atomic weight…ex…
Chlorine 35 and Chlorine 36
Totally non-reactive
CHEMICAL EQUATIONS – a method of showing what happens in a chemical reaction
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Metals lend/give electrons
Non-Metals take electrons
Example:
Sodium (Na) -metal
11 protons, 11 electrons
2,
8,
1
Sodium will give the one
Electron to Chlorine and have
A full outer shell (stable)
Sodium has lost an electron
+
Chlorine (Cl) –non-metal
17 protons, 17 electrons
2,
8,
7
Chlorine will take the one electron
from Sodium to have a full outer
shell (stable)
Chlorine has gained an electron
The Sodium atom will stick to the Chlorine atom by forming a BOND
Sodium and Chlorine are joined specifically by an IONIC BOND
It is no longer Sodium or Chlorine
It is now a Compound
The protons and electrons are able to cancel each other out…so the compound is NEUTRAL
SO……..
The first thing that happened is the sodium and chlorine atoms bumped into each other
Chlorine needed an electron and gained an electron
Sodium needed to give away an electron and did
The chlorine atom is no longer neutral because it has gained an electron making it an ion with a
-1 charge
The sodium atom is no longer neutral because it gave away an electron making it too and ion with
a +1 charge.
The sodium atom will stick to the chlorine atom by forming a BOND
More specifically, sodium and chlorine are now joined by an ionic bond
It is no longer chlorine or sodium
It is now an entirely new substance – a compound with entirely new properties that are different
than the properties of either sodium or chlorine.
Example: Chlorine is a poisonous green gas
Sodium is a highly reactive silver-colored metal
When ionic ally bonded they form a whole new substance –common table salt that is
harmless (NaCl)
4 STEPS IN AN IONIC REACTION
1.
2.
3.
4.
Atoms must BUMP into each other
Metals will give away electrons and non-metals will gain electrons
The neutral atoms turn into IONS
The atoms stick together as the opposite charges cause an ionic bond to form
METALS – lend or give away electrons
NONMETALS – borrow or take electrons
Positive valences react with negative valences
Example: Ba + S
yields
BaS
(Barium Sulfide)
Explanation: Barium has a valence of +2 and Sulfur has a valance of -2
They will bond to form Barium Sulfide
AL
Explanation:
+
F
yields
ALF
(Aluminum Fluoride)….BUT the formula is NOT right)
Aluminum has a valence of +3 and Fluorine has a valence of -1
It will take 3 Fluorine atoms to satisfy 1 Aluminum
The correct formula for Aluminum Fluoride is AlF3
BONDS – A bond is an invisible force that holds things together
There are 3 Types of Bonds (there are really more, but we will study just these three)
1. Ionic Bonds – A metal and a non-metal combine by trading electrons
2. Covalent Bonds – A non-metal and a non-metal combine by sharing electrons
3. Metallic Bonds – A metal and a metal combine
Note*
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Metallic Bonds are very strong physically and very weak chemically
Metals want to get rid of electrons
The atoms will stick together, but don’t make anything new – i.e. they will mix, but don’t really
react and they don’t make a new substance
RADICALS
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Radicals are polyatomic (made up of many atoms) ions that cannot be found on the periodic table.
You must get their valences from a chart
These are compounds that have come together and DO NOT want to separate.
They ACT AS ONE