Download Transition elements - Duplin County Schools

6-1 Development of the Periodic Table
1700s: 30 elements
-Cu, Ag, Au, H, O, N, C
J.W. Dobereiner, German chemist (1790-1849)
Triads: Elements grouped into sets of 3
-Similar properties
-Li, Na, K
Ca, Sr, Ba
Cl, Br, I
-Take average of 1st and 3rd =Center
J. A. R. Newlands 1865 English chemist
-Law of octaves (music)
-Properties of every 8th element were similar
-Increasing atomic mass
Dmitri Mendeleev 1869 (Russian)
-First Periodic table
-Arranged by increasing atomic mass
-Similar properties within a column
-Predicted properties of elements not yet
discovered
-Eka-silicon
-Germanium discovered 15 years later
HG.J Moseley 1913 (English)
-Arranged table by
-Increasing positive charge
-Increasing Atomic number
1
Periodic Law: When elements are arranged in order
of increasing atomic number, their physical and
chemical properties show a periodic pattern
6.2 Periodic Table
Groups or families: Vertical columns of elements
that have similar properties
Periods: Horizontal rows
-Increasing numbers of elements
1:2
2:8
3:8
4:18
5:18
6:32
7:32
s-, p- d-, f- block elements
s- block
-Groups 1 and 2
-Alkali metals and alkali earth metals
-s orbitals only
-Group 1 elements end in s1: 1 valence e-Group 2 elements end in s2: 2 valence e2
p-block
-2p1 Boron
-6 ed-block
-Middle of the table
-Transition metals
-10 e-, 10 blocks Sc (21) 3d1
f-block
28 elements that are placed below main body of
periodic table
-Usually do not fill orbitals in regular sequence
Metalloids: B, Si, As, Te, Se, Ge, Sb, At
Transition metals: d block
Inner transition metals: f block
-Lanthanides and actinides
3
Representative elements: s and p blocks
Periodic Trends
A. Atomic Radii: ½ the distance between nuclei of
identical atoms joined in a molecule
1. Period Trend
a. Decrease because of increasing positive
charge: e- pulled in
2. Group Trend
a. Increase
1. Shielding: e- s are not pulled in to the
positive nucleus because they are further
away and separated by other energy
levels
B. Ionization Energy: Energy required to remove an
e1. Periodic Trends
a. Increases across periods
b. Decreases down groups
2. Ion: An atom or a group of atoms that has a
charge ( + or -)
Na Na+
4
3. Ionization: Process that results in the formation of
an ion
-There is a large jump in ionization energy
when you remove an electron from a full
valence shell
-Blue line on chart
C. Ionic Radius: One-half the diameter of an ion in
an ionic compound
1. Cation: A positive (+) ion
a. Formed by losing e2. Anion: A negative (-) ion
a. Formed by adding e3. Period trend:
a. General decrease
1. Metals form cations
2. Nonmetals form anions
4. Group trend
1. General increase
D. Electronegativity: A measure of the ability of an
atom in a chemical compound to attract e1. Linus Pauling: Assigned numerical values to
the tendency of an atom to attract e2. Fluorine (4) Most electronegative
3. Periodic Trends
a. Period trend: Increases across
5
b. Group trend: Decreases down
E. Valence electrons: Outermost e-, occupying the
highest energy level
1. Involved with bonding with other atoms
2. Group 1: 1
3. Group 2: 2
4. Group 13-18
-Group # -10
Electron Affinities kJ/mol
Electron Affinity: The energy change that
occurs when an electron is acquired by a neutral
atom
A + e-  A- + energy
-Exothermic
A + energy + e-  A-Endothermic
-Unstable, will not last
Right side of table has lower electron
affinities
-Less energy to obtain an electron
6
Transition elements
-Order in which electrons are removed from all atoms
is exactly the reverse of the order given by the
electron configuration notation
-S is taken off before d
7