2. ELEMENTS
• A pure substance that can not be broken down into another substance.
• Every element has a unique set of properties.
• Some physical properties that are used to classify elements are boiling
point, melting point, color, and density.
• The Periodic Table of Elements is arranged according to these properties.
3.
4. PERIODIC TABLE OF ELEMENTS
• Created by Dmitri Mendeleev
• Contains 118 elements (modern
periodic table), with its atomic number,
atomic mass, etc.
• Most of the elements in the Periodic
table exist naturally as solids, some are
liquids, and other are gases.
• What are those elements that are
liquid? Gas?
5. PERIODIC TABLE OF ELEMENTS
• Period – horizontal rows of the periodic table, and there are seven periods in it.
- period 1 with 2 elements, period 2 and 3 with 8 elements, period 4 and 5
with 18 elements, period 6 has 32 elements, and period 7 still incomplete but holds
more than 32 elements.
- lanthanide and actinide series are part of period 6 and 7 respectively.
• Group or families – vertical columns
- group A as the representative elements
- group B as the transition metals
- IUPAC recommended the use of Group 1-18 but not widely used
6. REPRESENTATIVE ELEMENTS
Group Number Special Name Elements
IA Alkali metals Li, Na, k, Rb, Cs, and
Fr
IIA Alkaline earth metals Be, Mg, Ca, Sr, Ba,
and Ra
VIIA Halogens F, Cl, Br, I, and At
VIIIA Inert or Noble gases He, Ne, Ar, Kr, Xe,
and Rn
7. • Elements are divided into three groups:
1. Metals – comprises most of the elements in the periodic table, that are good
conductors of heat and electricity.
2. Nonmetals – poor conductors of heat and electricity.
3. Metalloids – int4ermediate to that of metals and nonmetals.
The next slide show the summary of the properties of metals, nonmetals, and
metalloids.
8. Metals Nonmetals Metalloids
Shiny Dull Shiny or dull
Ductile Brittle Ductile
Malleable - Malleable
Very high density Low density -
High melting point Low melting point -
Good conductors of heat and
electricity
Poor conductors of heat and
electricity
Conduct electricity better
than nonmetals
Reacts with water and
oxygen(forming rust and
corrosion)
- -
9. Nonmetals Metalloids
H, He, C, N, O, F, Ne, P, S, Cl, Ar, Se, Br,
Kr, I, Xe, and Rn
B, Si, Ge, As, Sb, Te, Po, At
Nonmetals and Metalloids
These elements are abundant in the environment, in minerals, rocks, soil,
etc. they can be found most in the commercial products available in the
market. Likewise, some of these elements may also be found in plants,
animals, and humans.
