Periodic Table.notebook
Grab your notebooks off the lab table and copy down the EQ's
September 22, 2014
Periodic Table
Unit 4­­­­­Periodic Table
Essential Questions: 1. Why are elements placed in a particular period or group on the periodic table?
2. Which elements on the periodic table are metals, nonmetals, metalloids, representative elements, transition elements, alkali metals, alkaline earth metals, halogens, and noble gases? Periods:
Horizontal rows (1-7)
Groups/Families continued...
Modern Periodic Table Arrangement
• Arranged according to
INCREASING ATOMIC #
• WHY?
> Elements with similar properties
fall in the same column
Groups (Families):
• Vertical columns (1-18 or 1A-8A and
1B-10B)
METALS, NON-METALS AND METALLOIDS
• Representative elements are found in
1,2 and 13-18 (or 1A-8A)
• all main group elements in the same
group have:
> same number of valence electrons
> same oxidation number
> similar chemical properties
1
Periodic Table.notebook
September 22, 2014
Representative Elements
• Found in groups 1, 2 and 13-18 (1A- 8A)
a) The rxn. of potassium with water.
(b) The rxn. of calcium with water. These photos illustrate that group 1 metals tend to be more reactive than group 2 metals. (c) The reaction of sodium metal and chlorine gas is very exothermic.
• Group 1: Alkali Metals
> one valence electron
> soft, silvery metals, easily cut with a knife
> very reactive, especially with air and water
• Group 2: Alkaline-earth metals
> two valence electrons
> harder, slightly less reactive & higher melting points
A
B
C
• Elements in groups 1 and 2 are very “active” (reactive) metals.
• Metals in group 1 are more reactive than metals in group 2
(because group 1 metals have lower ionization energies).
• Alkali metals are too reactive to be found free in nature – they
are always combined with some other element (ex: NaCl).
Alkaline earth metals are less reactive than alkali metals, but
still too reactive to be found as free elements in nature.
More representative Elements:
More representative Elements
• Group 17 (7A)
• Group 18 (8A)
> Halogens
– most reactive non-metals
« B/C they have high electronegativies and only need
one electron to fill their octets
« Halogens often react w/metals to form salts
Na(s) + Cl2(g) → NaCl(aq)
Transition Elements
> Noble Gases (AKA Inert Gases)
– Least reactive of all elements b/c they
have a full outer shell
– Ex: Helium
• Elements in d-Block
F-Block Elements:
• AKA transition metals
• Neither representative nor transition elements
• Includes groups 3-12 (1B-10B)
• Lanthanides: top row
• Metals with metallic properties
• harder, denser, less reactive & higher melting poitns
(expect for mercury) than groups 1&2
> AKA Rare Earth Elements
• Actinides: Bottom Row
> most are synthetic but all are unstable and radioactive
2
Periodic Table.notebook
Lets see it in ACTION!
https://www.teachingchannel.org/videos/periodic­table
September 22, 2014
Please put your PT Timelines on the back lab table over lab station 6. Have your PT Trends Straw lab out & ready, when the bell rings we will begin assembling our PT Trends!
Periodic Table Trends
UNIT 4 PERIODIC TABLE TRENDS
EQ's
> How do you explain the trend for increasing radius of atoms or ions on the PT?
> How do you explain the trend for ionization energy of elements on the PT?
> How do you explain the trend for electronegativity of elements on the PT? Atomic Radius
• 1/2 the distance between the nuclei of two covalentlybonded atoms
• Within a group: increases down a group
• Within a period: decreases across a period
> WHY?
– adding a proton and an electron each time you move
element to the right, added electrons are in the same
energy level
– more protons = stronger pull on the electrons in that
energy level, thus pulling them in tighter.
Ionic Radius
• Ions: atoms or groups of atoms with a positive or
negative charge
> Cation: Postively charged ion (loss of electron)
> Anion: Negatively charged (formed by gaining
electrons)
3
Periodic Table.notebook
September 22, 2014
Ionization Energy
Ionic Radius Continued...
• Ionic Radius – ½ the diameter of an ion in an ionic compound
• Within a period: decreases from left to right but resets when
transitions from non-metals (anions) to metals (Cations)
• Within a group: increases down a group
• Minimum amount of energy required to strip away one
electron from an atom of that element IN THE GASEOUS
STATE
• Within a period: increase across a period
• group 1 has the lowest ionization energy
• reflection of atomic radius
• Within a group: decreases down a group
Electronegativity
• The ability of an atom to attract electrons in a chemical bond
> Remember the goal for all atoms is to be STABLE
• Noble Gasses are the most stable elements b/c they have a
full octet
• Most electronegative is flourine
• Within a period: increases left to right
• Within a group: decreases down a group
Electron Affinity
• the energy change associated with adding an
electron to an atom IN ITS GASEOUS STATE
• Generally become more negative left to right
across the periodic table
4
Periodic Table.notebook
September 22, 2014
5