An atom is the smallest amount of a chemical element that can exist in this universe. They are made up of even smaller subatomic particles like the protons, neutrons, and electrons. Protons and neutrons, held by the nuclear force is what makes up the positively charged atomic nucleus in the centre. The negatively charged electrons exist around the nucleus in different energy states called as orbitals, defined by the electromagnetic force between the nucleus, which is governed by the uncertainty principle. The unique chemical property of all the atoms in the universe arises from the number of protons found in the nucleus, which makes up most of the atomic mass.
Frequently Asked Questionsedit
Where did the first atom come from?edit
The very first atomic nuclei to form are deuterium. It is believed to be created three minutes after the Big Bang, by the process called nucleosynthesis. But due to the high temperature, the energy per particle was so high that they were destroyed the moment they formed. The stable deuterium nuclei were only formed when the universe cooled enough below its binding energy. These nuclei then formed helium nuclei at that time in the universe, later being the cause for the abundance of hydrogen and helium in the universe.
How do atoms form compounds?edit
Atoms of different elements, under right conditions, form a chemical compound by forming chemical bonds with each other. By bonding with another atom and forming a compound, the outer shells of those atoms share electrons with each other to stabilize themselves.
The basic unit of a compound is a molecule. However, not all molecules are compounds. For example, two hydrogen atoms form a stable hydrogen molecule by binding to itself. When this hydrogen molecule bonds with oxygen, it forms a bigger molecule called water, which is also a compound.
Why do electrons don't fall into the nucleus?edit
Electrons exist in distinctive energy levels around the nucleus. This is because of the nature of the electron itself. Locating an electron with absolute certainty is impossible. Due to the uncertainty principle, trying to confine an electron to smaller space would eventually increase the standard deviation of electron's position. And hence, the energy of the electron increases. This also means that the electron would have a higher momentum and it would tend to stay away from the nucleus more. The existing electrostatic attraction from the nucleus and the tendency of the electron to move away from the nucleus cancel out at a certain point from the nucleus. This forms the electron's stable configuration called orbital, where the probability of finding an electron will be higher. This is why electrons do not fall into the nucleus.