In-periodic table, in full periodic table of the elements, in chemistry, the
organized array of all the chemical elements in order of Increasing atomic
number-i.e.. the total number of protons in the atomic nucleus. When the
chemical elements are thus arranged, there is a recurring pattern called the
“periodic law” in their properties, in which elements in the same column
(group) have similar properties. The initial discovery, which was made by
Dmitry I. Mendeleyev in the mid-19th century, has been of inestimable value
in the d”velopment of chemistry.
It was not actually recognized until the second decade of the 20th century
that the order of elements in the periodic system is that of atomic numbers,
the integers of which are equal to the positive electrical charges of the
atomic nuclei expressed in electronic units. In subsequent years great
progress was made in explaining the periodic law in terms of the electronic
structure of atoms and molecules. This clarification has increased the value
of the law, which is used as much today as it was at the beginning of the
20th century, when it expressed the only known relationship among the
elements.
Metals
Metals constitute the greatest number of elements in the periodic table. They
are located at the left part, middle part, and the bottom part of the periodic
table. These elements have characteristics that are distinct from the other
elements
Properties of Metals
→Metals are lustrous in nature. They have a shiny appearance.
→Metals are malleable.
→Metals are malleable because their atoms can move past each other
without breaking the metallic bond, therefore, retaining the structure of the
metals.
→Metals are ductile, Metals are ductile for the same reason that the atoms of
metals have the ability to move past each other without breaking the
metallic bond.
→Metals are good.conductors. of heat and electricity
→Metals are solid at room temperature except mercury.
→Most metals are hard
→Metals have high densities.
Non- Metals
→Non-metals are elements that lack or do not have the characteristics of
metals.
→Non-metals are located at the rightmost part of the periodic table, except
for hydrogen, which is at the leftmost part.
→Non- metals have a dull appearance. They do not have a shiny surface or
appearance. However, iodine, a non metal, is lustrous.
→Non-metals are britlle. They are neither ductile or malleable, meaning they
do not have the ability to be drawn into thin wires or to be hammered into
thin sheets.
→Non-metals are poor conductors of heat and electricity because they do not
have free electrons that are typical of metals.
→They are also good insulators.
→Non metals may exist in three state, at room temperature.
→They have low densities. They have weak attractive forces between their
atoms making them less dense.
Metalloids
→Metalloid are elements which have the properties of both metals and non-
metals.
Example:
Boron, silicon, germanium, arsenic, antimony, tellurium, polonium, and
astatine, however, are sometimes not considered as metalloids.
Compounds
→Compounds are substances composed of two or more kinds of atoms that
are chemically bonded together in fixed proportions.
→One of the most common examples of compounds is water, having two
hydrogen atoms and one oxygen atom. Compounds can be classified as
acids, bases, or salts.
Some common compounds and their uses
Compound Common Chemical Uses
name compound formulas
Carbonic acid Carbon dioxide CO2 Uses by plants
gas during
photosynthesis.
Table salt Sodium chloride NaCl Used in food
Baking soda Sodium NaHCO3 Used in baking
bicarbonate and for cleaning
purposes
Limestone Calcium CaCO3 Used as
carbonate construction
Vinegar Acetic acid CH3COOH Used as
condiment and
for cleaning
purposes
Rubbing alcohol Isopropyl (CH3) 2 CHOH Used as a
alcohol disinfectant
5 Main Branches of Chemistry
• Organic Chemistry Study of the structures, composition, properties and
reactions of compounds that contain carbon -hydrogen bond.
• Inorganic Chemistry Study of the composition, properties and behaviors of
inorganic compounds such as metals and minerals.
• Physical Chemistry Studies the interactions between chemical elements
and concepts related to physics like time and energy.
• Biochemistry Study of the chemical processes within living thing.
• Analytical Chemistry Branch of chemistry that uses chemical analysis to
define types of matter and determine their quantities.
Everything that exists is made up of matter, Atoms and substances are made
up of pieces of matter. The atoms that make up the objects we see and touch
every day are made up of matter. All that has mass and occupies space has
volume is known as matter. The amount of matter in an object measured by
its mass.
Physical Properties of Matter
• Matter is made up of tiny
called atoms and can be represented
or explained as something that takes
up space. It must display both the
mass and volume properties,
•Properties are the characteristics
that enable us to differentiate one
material from another. A physical
property is an attribute of matter
that is independent of its chemical
composition.
• Density, colour, hardness, melting and boiling points, and electrical
conductivity are all examples of physical properties.
• Any characteristic that can be measured, such as an objects density,
colour, mass, volume, length, malleability, melting point hardness, odour,
temperature, and more, are considered properties.
Intensive and Extensive Properties of Matter
Both the physical and chemical properties of matter are either extensive or
intensive. Extensive properties including mass and volume are proportional
to the amount of matter being weighed. Density and colour, for example, are
not affected by the amount of matter present.
Intensive properties of matter – An intensive property is a bulk property,
which means it is a system’s local physical property that is independent of
the system’s size or volume of material. Intensive properties are those that
are independent of the amount of matter present. Pressure and temperature,
for example, are intensive properties.
Extensive property of matter – A property that is dependent on the amount
of matter in a sample is known as an extensive property. Extensive
properties include mass and volume. The scale of the system or the volume
of matter in it determines the extensive property of the system. Extensive
properties are those in which the value of a system’s property is equal to the
sum of the values for the parts of the system.
Chemical Properties of Matter
Chemical properties are characteristics that can only be measured or
observed as matter transforms into a particular type of matter. Reactivity,
flammability, and the ability to rust are among them. The tendency of matter
to react chemically with other substances is known as reactivity.
Flammability, toxicity, acidity, the reactivity of various types, and heat of
combustion are examples of chemical properties.
Reactivity – The tendency of matter to combine chemically with other
substances is known as reactivity. Certain materials are highly reactive,
whereas others are extremely inactive. Potassium, for example, is extremely
reactive, even in the presence of water. A pea-sized piece of potassium
reacts explosively when combined with a small volume of water.
Flammability – The tendency of matter to burn is referred to as flammability.
As matter burns, it reacts with oxygen and transforms into various
substances. A flammable matter is anything like wood.
Toxicity – Toxicity refers to the extent to which a chemical element or a
combination of chemicals may harm an organism.
Acidity – A substance’s ability to react with an acid is a chemical property.
Some metals form compounds when they react with different acids. Acids
react with bases to create water, which neutralizes the acid.
