chapter 6 notes

1. Chapter 6
The Periodic Table
Section 6.1 & 6.2
Organizing & Classifying Elements
1

2. Why is the Periodic Table important
to me? • The periodic table is the
most useful tool to a
chemist.
• You get to use it on
every test.
• It organizes lots of
information about all the
known elements.
2

3. Pre-Periodic Table Chemistry …
• …was a mess!!!
• No organization of
elements.
• Imagine going to a grocery
store with no organization!!
• Difficult to find information.
• Chemistry didn’t make
sense.
3

4. Dmitri Mendeleev
Father of the Table
HOW HIS WORKED…
• Put elements in rows by
increasing atomic weight.
• Put elements in columns
by the way they reacted.
SOME PROBLEMS…
• He left blank spaces for
what he said were
undiscovered elements.
(Turned out he was
right!)
• He broke the pattern of
increasing atomic weight
to keep similar reacting
elements together.
4

5. The Current Periodic Table
• Mendeleev wasn’t too far off.
• Now the elements are put in rows by increasing
ATOMIC NUMBER!!
• The horizontal rows are called periods and are
labeled from 1 to 7.
• The vertical columns are called groups are
labeled from 1 to 18.
5

6. Groups…Here’s Where the Periodic
Table Gets Useful!!
• Elements in the
same group
have similar
chemical and
physical
properties!!
• (Mendeleev did that on purpose.)
Why??
• They have the same
number of valence
electrons.
• They will form the same
kinds of ions.
6

7. P
Zn As
Sb
Pt Bi
Midd. -1700
Cr Mn
Li
K
N O F
Na
BBe
H
Al Si Cl
Ca Ti V Co Ni Se Br
Sr Y Zr Nb Mo Rh Pd Cd Te I
Ba Ta W Os Ir
Mg
Ce Tb Er
Th U
1735-1843
Discovering the Periodic Table
C
S
Fe Cu
Ag Sn
Au Hg Pb
Ancient Times
He
Sc Ga Ge
Rb Ru In
Cs Tl
Pr Nd Sm Gd Dy Ho Tm Yb
La
1843-1886
Ne
Ar
Kr
Xe
Po Rn
Ra
Eu Lu
Pa
Ac
1894-1918
Tc
Hf Re At
Fr
Pm
Np Pu Am Cm Bk Cf Es Fm Md No Lr
1923-1961
Rf Db Sg Bh Hs Mt
1965-
7

8. In the modern periodic table, elements are arranged in
order of increasing atomic number.
There are seven rows,
or Periods, in the
table.
Each period
corresponds to a
principal energy level.
1
2
3
4
5
6
7
6
7
8

9. The elements within
a column, or group,
in the table have
similar properties.
The Three classes of elements are metals, nonmetals,
and metalloids.
9

10. 10

11. Metals
11

12. Metals
About 80% of the elements are metals.
Characteristics of metals
1. Good conductors of heat and electric current.
2. Solids at room temperature.
3. Ductile , can be drawn into wires.
Except mercury is liquid.
4. Most metals are malleable.
5. Lose electrons. (will be explained next chapter)
12

13. Nonmetals
13

14. Nonmetals
Elements in the upper-right corner of the periodic
table.
Characteristics of nonmetals
3. Most nonmetals are gases at room
temperature.
1. Poor conductors of heat and electric current
Few of them are solids like sulfur and phosphorus, they
are brittle
Except carbon
2. Gain electrons. (will be explained next chapter)
14

15. Semi-metals or Metalloids
15

16. Metalloids
Elements that have similar properties to metals
and nonmetals.
They may behave like metals and sometimes like
nonmetals.
e.g. pure silicon is a poor conductor of electric
current, like nonmetals.
But if a small amount of boron is mixed with silicon,
it conducts electric current
16

17. The periodic table displays the symbols and names of
elements, along with information on the structure of the
atoms.
Elements can be sorted into different groups based on
their electron configurations.
17

18. Alkali Metals
Group 1 elements are called alkali metals.
18

19. Alkaline Earth Metals
Group 2 elements are called alkaline earth metals.
19

20. Halogens
Group 7 elements are called halogens.
They often form salts.
20

21. 21

22. Transition Metals
are elements that usually displayed in the main
body of a periodic table.
e.g. copper, silver, zinc, iron.
All Transition metals have electron
configurations that end up with d orbitals.
22

23. Noble Gases
23

24. This is because their s and p sublevels are completely filled.
Group 8 are Noble gases.
They rarely take part in a reaction.
Noble Gases
24

25. 25

26. Inner Transition metals
are elements that appear below the main body of
the periodic table
All inner Transition metals have electron
configurations that end up with f orbitals.
e.g. lanthanum, actinium
(Lanthanides, Actinides)
26

27. Section 6.3
Periodic Trends
27

28. Atomic radius is one half the distance between the nuclei of
two atoms of the same element when the atoms are joined.
In general, atomic size increases from top to bottom within
a group.
In general, atomic size decreases from left to right across
a period.
Ions
Positive and negative ions form when electrons are
transferred between atoms.
An ion with a positive charge is called a cation. (e.g. Na1+)
An ion with a negative charge is called an anion. (e.g. Cl1-)
28

29. The energy required to remove an electron from an
atom is called ionization energy.
First ionization energy tends to decrease from top to bottom
within a group.
First ionization energy tends to increase from left to right
across a period.
Cations are always smaller than the atoms from which they form.
Anions are always larger than the atoms from which they form.
Electronegativity is the ability of an atom to attract electrons
when the atom is in a compound.
In general, electronegativity values decrease from top to
bottom within a group and increase from left to right. 29