Download Elements and The Periodic Table

Elements and the Periodic Table
Elements are the simplest form of matter and are made up of the same atoms. They
cannot be broken down, but they can lose their individual physical and chemical
properties in a compound. Most elements are monatomic; their elementary particles
contain a single unit, the atom. All the metals and some non-metals are monatomic. A
monatomic element should be written without a subscript because the number 1 is
understood (Examples: Na, Fe, Ra, U, Al). Seven elements are diatomic; their
elementary particles, when formed, contain two like atoms. The subscript 2 should be
used.
The Seven Diatomic Elements
I2
Iodine
Br2 Bromine
Cl2 Chlorine
F2 Fluorine
O2 Oxygen
N2 Nitrogen
H 2 Hydrogen
(Memory helper: I Bought Cement For Our New House)
Although subscripts are not used on the periodic table, know that Phosphorus (P4) is
tetratomic and Sulfur (S8) is octatomic.
There are more than 116 elements on the periodic table; ninety elements are found in
nature. All elements beyond #92 (uranium) are laboratory-made and radioactive.
Technetium (#43) and promethium (#61), although less complex than uranium, are not
found in nature.
Elements in the Body
O2 Oxygen
65.0%
C
Carbon
17.5%
H2 Hydrogen 10.2%
N2 Nitrogen
2.4%
Ca Calcium
1.6%
All others 3.3%
The earth’s crust, deep below the oceans, is made up of three kinds of rocks. These rocks
are composed mostly of two elements, oxygen and silicon, which account for more that
75% of the crust’s weight.
Elements in the Earth’s Crust
O2 Oxygen
49.5%
Si
Silicon
25.8%
Al
Aluminum 7.5%
Fe
Iron
4.7%
Ca Calcium
3.4%
*All others
9.1%
*Such as sodium, magnesium, and hydrogen
Oxygen is colorless and odorless; it makes up one-fifth of the air. Silicon, in its pure
state is a brown powder, or dark gray or black crystal.
The periodic table arranges elements in order of increasing atomic numbers. The
atomic number is the number of protons; since an atom is electrically neutral, the atomic
number also indicates the number of electrons surrounding the nucleus.
Periods – horizontal rows, ordered in increasing size and atomic number, elements
typically have same number of energy levels
Groups – families, vertical column, have similar physical and chemical properties
The current IUPAC system numbers the groups 1-18. An older system (still in use)
identifies each group by a number and the letter A or B. The group A elements are made
up of Group IA (1A) through Group VIIA (7A) and Group VIIIA. Group A elements
(Groups 1, 2, and 13-18) are called representative elements because they exhibit a wide
range of both physical and chemical properties. The representative elements can be
divided into three broad classes:
1. Metals – (Except hydrogen) on left side of periodic table
2. Alkali metals – Group I (1A), except for hydrogen-react vigorously, even
explosively with water
3. Alkaline earth metals – Group 2 (IIA)
Most of the remaining elements that are not Group A elements are also metals. These
include the transition metals (Groups 3-12) and the inner transition metals, which
together make up the Group B elements. Copper, iron, gold, and silver are familiar
transition metals. The inner transition metals, which appear below the main body of the
periodic table, are also called rare-earth elements.
Chalcogens – Group 16 (VIA) , ore-forming
Halogens – Group 17 (VIIA) , combine with metals to form salts
Noble gases – Group 18 (Group VIIIA or 0) , inert gases, tend to not react
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Kinds of Elements
I. Metals
1. Luster, shine
2. Color- gray, orange, yellow
3. Solids, except mercury which is a liquid at room temperature
4. Malleability – hammered into sheets
5. Ductility – ability to be drawn into wire
6. Conductivity of electricity – in both the solid and liquid phases
7. Relatively high boiling point
8. Conductivity of heat
9. Tenacity – strong, resist being pulled apart
10. Relatively high melting point
11. Except for hydrogen, metals are on the left side of the periodic table
12. Francium is the most active metal
II. Non-metals
1. Generally have low boiling points
2. Soft solid
3. Some (sulfur) are brittle solids
4. Some (oxygen and chlorine) are gases at room temperature
5. Generally nonlustrous
6. Generally poor conductors of electricity
7. One, bromine, is a fuming dark-red liquid at room temperature
8. Includes noble gases (Group VIIIA or 0) and halogens (Group VIIA)
9. Occupy upper right corner of periodic table
10. Fluorine is the most active non-metal
III. Metalloids
1. Semi-metals
2. Properties of metals and non-metals
3. Sometimes brittle
4. Border bold black line on the periodic table
5. Boron, silicon, germanium, arsenic, selenium, antimony, tellerium, polonium,
astatine
6. Silicon and germanium are used in the manufacture of computer chips and solar
cells
IV. Noble gases
1. Nonreactive
2. Outer energy level is filled
3. Colorless
4. Group 18 (VIIIA or 0)
5. Helium, neon, argon, krypton, xenon, radon
Liquid elements – bromine, mercury
Gas elements – hydrogen, nitrogen, oxygen, fluorine, chlorine, helium, neon, argon,
krypton, xenon, radon