The table in which chemical elements are arranged graphically is called the ‘Periodic table’. These are organized by atomic number, electron configurations, and chemical properties. The elements are arranged in rows and columns according to their atomic structure and chemical properties.
Elements in the Periodic table:
The periodic table currently has 118 elements, each represented by a unique symbol and atomic number. The elements are arranged in rows and columns according to their atomic structure and chemical properties. Chemical and physical properties are unique for each element.
There is a unique symbol and atomic number for each element in the periodic table. The elements in the same row (called a period) have the same number of electron shells. On the other hand elements with similar chemical and physical properties are placed in the same column called group.
The elements in the periodic table can be divided into several categories, including metals, nonmetals, and metalloids.
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Metals:
- Elements that are generally shiny, malleable, and conductive. Examples include gold (Au), silver (Ag), and copper (Cu).
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Nonmetals:
- Elements that are generally dull, brittle, and poor conductors of heat and electricity. Examples include carbon (C), sulfur (S), and chlorine (Cl).
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Metalloids:
- Elements with both metallic and nonmetallic characteristics are called metalloids. Silicon with symbol Si and germanium – Ge are the examples of metalloids.
There are also other specific categories such as Alkali metals, Alkali Earth metals, Lanthanides, and Actinides, which have certain specific properties. Some elements are also radioactive and can be found in nature in small amounts, these are called radioactive elements.
Trends in the Periodic table:
The periodic table has several trends that can be observed as you move across a row (period) or down a column (group).
These trends are related to the atomic structure and chemical properties of the elements.
Trends across a period:
- There is a decrease in atomic size as we go from left to right across a period.
- Ionization energy will increases from left to right across a period.
- As we move from left to right across a period in the periodic table electronegativity increases.
Trends down a group:
- As we move down the group atomic size increases.
- Ionization energy also decreases as we are going down in a group.
- Electronegativity decreases as you move down a group.
- There is an increase in metallic character as we go down a group.
- Elements become more reactive as going down the group.
In general, elements in the left side of the table are more metallic and have lower ionization energy and electronegativity. Elements on the right side of the table are more nonmetallic and have higher ionization energy and electronegativity.
It’s important to note that these trends are general tendencies and exceptions do exist.
