Basics of
Chemistry
BY-
Krrishiv Maurya
pg. 1
, Chapter 1
Introduction to
Chemistry
Chemistry is the branch of science that deals with the study of matter—its
composition, structure, properties, and the changes it undergoes during chemical
reactions. Everything around us, such as air, water, food, medicines, and
materials, is made of matter. Chemistry helps us understand how substances are
formed, how they interact, and how they can be used for the benefit of society.
Matter is anything that has mass and occupies space. It commonly exists in
three physical states: solid, liquid, and gas. Solids have a fixed shape and
volume, liquids have a fixed volume but no fixed shape, and gases have neither
a fixed shape nor volume. Matter is made up of extremely small particles called
atoms and molecules.
An atom is the smallest unit of an element that retains its chemical properties.
According to modern atomic theory, an atom consists of three main subatomic
particles: protons, neutrons, and electrons. Protons carry a positive charge and
are present in the nucleus, along with neutrons, which have no charge. Electrons
carry a negative charge and revolve around the nucleus in fixed energy levels or
shells. The number of protons in an atom determines the atomic number, while
the total number of protons and neutrons gives the mass number.
An element is a pure substance made up of only one kind of atom. Elements are
represented by symbols and are systematically arranged in the periodic table,
which helps scientists study their properties and predict their behavior. When
atoms of different elements combine in a fixed ratio, they form compounds,
such as water (H₂O) and carbon dioxide (CO₂).
pg. 2
Chemistry
BY-
Krrishiv Maurya
pg. 1
, Chapter 1
Introduction to
Chemistry
Chemistry is the branch of science that deals with the study of matter—its
composition, structure, properties, and the changes it undergoes during chemical
reactions. Everything around us, such as air, water, food, medicines, and
materials, is made of matter. Chemistry helps us understand how substances are
formed, how they interact, and how they can be used for the benefit of society.
Matter is anything that has mass and occupies space. It commonly exists in
three physical states: solid, liquid, and gas. Solids have a fixed shape and
volume, liquids have a fixed volume but no fixed shape, and gases have neither
a fixed shape nor volume. Matter is made up of extremely small particles called
atoms and molecules.
An atom is the smallest unit of an element that retains its chemical properties.
According to modern atomic theory, an atom consists of three main subatomic
particles: protons, neutrons, and electrons. Protons carry a positive charge and
are present in the nucleus, along with neutrons, which have no charge. Electrons
carry a negative charge and revolve around the nucleus in fixed energy levels or
shells. The number of protons in an atom determines the atomic number, while
the total number of protons and neutrons gives the mass number.
An element is a pure substance made up of only one kind of atom. Elements are
represented by symbols and are systematically arranged in the periodic table,
which helps scientists study their properties and predict their behavior. When
atoms of different elements combine in a fixed ratio, they form compounds,
such as water (H₂O) and carbon dioxide (CO₂).
pg. 2
