DVD: USING THE PERIODIC TABLE
(NOTES)
January 7, 2014
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Over 100 elements have been discovered
Each element has a unique set of properties and behaviors.
Periodic table used to identify the similarities and differences of elements
If you know the location of an element on the periodic table you can determine their properties and how
they will react.
Dmitri Mendeleev: 1869 organized first periodic table
Group/family are vertical
Undiscovered elements have empty spaces
Rows called periods
The first period Hydrogen (H) and Helium (He)
Light, colorless, odorless, tasteless at room temperature
Make up most of the universe (9 out of 10 elements in universe are H, the rest are He)
H makes the sun and stars shine
nuclear reaction, releases tremendous energy and produces He
Key Point: Nuclear reactions
Key Point: Chemical reactions involve electrons
Dot structures (valence electrons)
Hydrogen (H) has one electron (one dot)
Helium (He) has two electrons (two dots)
Period one elements have one energy level and can hold a maximum of two electrons.
When an energy level is full, it is stable
When an energy level is not full, it is unstable
He does not react with other elements and stable
H forms many bonds
Second Period
Gradual transition from shiny, solid metals to gaseous non-metals
Key Point: metals get harder and less reactive from left to right and nonmetals get more reactive
from left to right
Lithium, lightest and softest, reacts with air and water
Beryllium less reactive, most toxic elements
Key Point: metalloid is an element with a blend of metallic and non-metallic properties.
Boron (B) less reactive than Be
carbon atoms bond to one another indefinitely
example, diamond
Nitrogen (N) (diatomic, gas, non-metal)
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Oxygen (O) (diatomic, gas non-metal) reactive and highly flammable
Fluorine (F), (gas, non-metal) highly reactive, can form explosive compounds
Neon (Ne), (unreactive gas, on-metal)
electron arrangement determines reactivity
have second energy level
Key Point: only electrons in the valence shell (level) are involved in chemical reaction.
valence electrons are shown as dots around the symbol
valence electrons determine the reactivity of an element
Key Point: Every period ends with a noble gas
most reactive elements Li and F
noble gases are non-reactive
most reactive elements are closest to noble gases on the table
Trends of metal reactivity
75% of elements are metals
The easier it is for an element to loose electrons, the more reactive it is
smaller atoms, easier to loose electrons
group one electrons loose one electron
Key Point: Ionization energy is the energy required to pull electrons away from an isolated atom.
groups two looses two electrons
Alkali Metals (group/family 0ne)
Never found uncombined in nature
Need to be stored in oil or gas to avoid reactivity
The lower the element on the table, the more violent the reaction (more reactive)
Alkali Earth Metals (group/family two)
React slower than group one
used in fireworks
metals share valence electrons (sea of electrons)
harder than group one
Key Point: semiconductors only conduct electricity at high temperatures
Group 13 (aluminum Group)
All group 13 react and release lots of energy
low melting points
Group 3-12 Transition metals
Elements differ in properties
There is not pattern because of partially filled levels
don’t have a pattern in valence electrons
Group 14 Carbon Family
C does not conduct electricity in diamond form, covalent bonds (nonmetal)
atoms react like a metal if the electrons are easier to pull
as the elements go down in the group, the more metallic its behavior (same for groups 13-16)
Location of elements is based on its behavior and properties
Group 13-16
Elements become more metallic as they go down on the table.