Atoms Around Us
What are atoms?
Atoms are the smallest unit of matter and the building blocks of everything around us. The term — atom — is derived from a Greek word ‘Atomos’ that means “Indivisible (cannot be divided)” source.
Atoms can join together to form molecules, which in turn form most of the objects around us. When atoms join together, they form molecules, which form cells, which form tissues, which form our organs and people and our planets and galaxies, and so on.
A question can arise in your mind that if everything is made of atoms in the universe, then why are they different from each other, while Periodic Table of Elements have only 118 elements in total.
Answer, different combinations of atoms produces different substances. Let’s understand it with the example of alphabet letters. In English, there are only 26 letters, but we can make thousands of words out of them.
Similarly, in chemistry there are only 118 known elements that exits in the universe. But when we combine them, it produces millions of different substances.
Suppose we take three elements from the Periodic Table of Elements: C (carbon), H (hydrogen, and O (oxygen).
When one atom of C (carbon) and two atoms of O(oxygen) combine together chemically, they form CO2(carbon dioxide gas).
Similarly, when two atoms of H(hydrogen) and one atom of O(oxygen) combine together chemically, they form H2O(water).
When two atoms of H (hydrogen) and two atoms of O (oxygen) combine together chemically, they form H2O2 (hydrogen peroxide).
What is an element?
An element is a substance that is made up of atoms that all have the same number of protons in their nucleus. The number of protons in an atom’s nucleus is called its atomic number, and it determines the element the atom represents. For example, all carbon atoms have 6 protons in their nucleus, so carbon is an element.
An element cannot be separated or broken down into simpler substances by physical or chemical changes. An atom is the unit part of an element.
For example, Carbon(C) is an element that is made of carbon atoms.
There are 118 known elements, which are organized into the periodic table based on their atomic number and other properties. Each element has its own unique set of characteristics and behaviors, which are determined by the arrangement and behavior of its atoms.
Some examples of elements are: hydrogen, carbon, oxygen, gold, boron, sodium, etc.
Difference between an atom and an element
Atom
- Atom is the unit part of an element.
- Atoms are further composed of extremely tiny (subatomic) particles called electrons, protons and neutrons.
- There are 92 kinds of atoms that exist in nature.
- The atoms combine to form molecules
Element
- A basic substance made up of the same type of atom that cannot be separated or broken down into simpler substances by physical or chemical changes.
- Element is composed of only one type of atom.
- There are a total of 118 known elements.
- They combine to form a chemical compound.
Parts of an atom
- Electron,
- Proton and
- Neutron
Electrons in an atom are arranged in shells around the nucleus. The outermost shell is called the valence shell, and the number of electrons in the valence shell determines how the atom will interact with other atoms and molecules. Atoms can gain or lose electrons to form ions, or they can share electrons in a covalent bond to form molecules.
They carry a negative electrical charge (-ve). The size of electron is much smaller than protons or neutrons but the number of electrons are always equal to number of protons. For example, a carbon atom have six electrons as well as six protons. The equal number of electron and proton makes atoms electrically neutral.
Protons are positively charged particles found in the nucleus of an atom. The number of protons in an atom’s nucleus determines the element the atom represents.
Neutrons carry no electrical charge at all. These neutral particles found in the nucleus of an atom. They have a mass that is slightly larger than that of protons.
Properties of Atoms
- Atomic number: This is the number of protons in the nucleus of an atom, which determines the element it belongs to.
- Mass number: This is the total number of protons and neutrons in the nucleus of an atom.
- Atomic mass: This is the mass of an atom, which is approximately equal to the sum of the masses of its protons and neutrons.
- Atomic radius: This is a measure of the size of an atom, which is determined by the distance between the center of the nucleus and the outermost electrons.
- Ionization energy: This is the energy required to remove an electron from an atom or ion.
- Electronegativity: This is a measure of an atom’s ability to attract electrons towards itself in a chemical bond.
What is the size of the atom?
The size of an atom is difficult to define precisely because the electrons that orbit the nucleus are constantly moving and do not have a fixed position. However, atoms do have a characteristic size known as the atomic radius, which is a measure of the distance between the center of the nucleus and the outermost electrons in the atom.
The atomic radius of an atom is generally determined by the size of the nucleus and the energy and number of the electrons in the outermost shell. Atoms with more protons in the nucleus and/or more electrons in the outermost shell tend to have larger atomic radii, while atoms with fewer protons and/or fewer outer shell electrons tend to have smaller atomic radii.
In general, atoms range in size from about 0.1 to 0.5 nanometers (nm). For comparison, a nanometer is about 100,000 times smaller than the diameter of a human hair.
Difference between atom, molecule and element
An atom is the basic unit of matter that makes up all elements. It is composed of a nucleus, which contains protons and neutrons, surrounded by electrons that orbit the nucleus.
The number of protons in an atom’s nucleus determines the element to which it belongs to. For example, an atom with six protons in its nucleus is a carbon atom, and an atom with 92 protons in its nucleus is a uranium atom.
A molecule is a group of atoms that are bonded together. (H2, O2, H2O, C6H12O6, etc…).
Molecules can be composed of atoms of the same element (such as oxygen molecules, which are made up of two oxygen atoms) or of different elements (such as water molecules, which are made up of two hydrogen atoms and one oxygen atom).
Molecules can be small and simple, like the oxygen molecule, or large and complex, like proteins and DNA.
An element is a basic substance made up of the same type of atom that cannot be separated or broken down into simpler substances by physical or chemical changes.
There are 118 known elements, which are arranged on the periodic table according to their atomic number (the number of protons in the nucleus).
Elements can be classified as metals, nonmetals, or metalloids, based on their chemical and physical properties.
To summarize, atoms are the basic units of matter that make up all elements, molecules are groups of atoms that are bonded together, and elements are defined by the number of protons in their nuclei.
Things to Remember
➤ Atoms are the smallest unit of matter and the building blocks of everything around us.
➤ Atoms are composed of extremely tiny (subatomic) particles called electrons, protons and neutrons..
➤ There are 92 kinds of atoms exist that in nature.
➤ Nucleus is the center of an atom containing protons and neutrons.
➤ The number of protons in an atom’s nucleus is called its atomic number.
➤ The electrons in an atom are arranged in shells around the nucleus. The outermost shell is called the valence shell.
➤ Electrons carry a negative electrical charge (-ve)
➤ The size of electron is much smaller than protons or neutrons.
➤ The number of electrons are always equal to number of protons.
➤ Protons are positively charged particles found in the nucleus of an atom.
➤ Neutrons carry no electrical charge at all. These neutral particles found in the nucleus of an atom.
➤ Atomic number is the number of protons in the nucleus of an atom, which determines the element it belongs to.
➤ Mass number is the total number of protons and neutrons in the nucleus of an atom.
➤ Atomic mass is the mass of an atom, which is approximately equal to the sum of the masses of its protons and neutrons.
➤ Atomic radius is a measure of the size of an atom, which is determined by the distance between the center of the nucleus and the outermost electrons.
➤ Ionization energy is the energy required to remove an electron from an atom or ion.
➤ Electronegativity is a measure of an atom’s ability to attract electrons towards itself in a chemical bond..
➤ Atoms range in size from about 0.1 to 0.5 nanometers (nm).
➤ A molecule is a group of atoms that are bonded together. (H2, O2, H2O, etc.
➤ An element is a basic substance made up of the same type of atom that cannot be separated or broken down into simpler substances by physical or chemical changes.
➤ There are 118 known elements, which are arranged on the periodic table according to their atomic number (the number of protons in the nucleus).
➤ Elements can be classified as metals, nonmetals, or metalloids, based on their chemical and physical properties.