What is Atom?

An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across. They are so small that accurately predicting their behavior using classical physics—as if they were tennis balls, for example—is not possible due to quantum effects. 

Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons.

 The nucleus (or center) of an atom is made up of protons and neutrons. The number of protons in the nucleus, known as the "atomic number," primarily determines where that atom fits on the Periodic Table. The number of protons in the nucleus also defines in large part the characteristics of an atom—is it a gas or a metal, for example. 

Two atoms with an identical number of protons in their nuclei belong to the same element. An element, like hydrogen, oxygen or iron, is a substance that cannot be broken down of a nuclear reaction—into anything else. In other words, one element cannot be transformed into another (again, with the except of nuclear reactions)

An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across. They are so small that accurately predicting their behavior using classical physics—as if they were tennis balls, for example—is not possible due to quantum effects. 

Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons.

 The nucleus (or center) of an atom is made up of protons and neutrons. The number of protons in the nucleus, known as the "atomic number," primarily determines where that atom fits on the Periodic Table. The number of protons in the nucleus also defines in large part the characteristics of an atom—is it a gas or a metal, for example. 

Two atoms with an identical number of protons in their nuclei belong to the same element. An element, like hydrogen, oxygen or iron, is a substance that cannot be broken down of a nuclear reaction—into anything else. In other words, one element cannot be transformed into another (again, with the except of nuclear reactions)

An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across. They are so small that accurately predicting their behavior using classical physics—as if they were tennis balls, for example—is not possible due to quantum effects. 

Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons.

 The nucleus (or center) of an atom is made up of protons and neutrons. The number of protons in the nucleus, known as the "atomic number," primarily determines where that atom fits on the Periodic Table. The number of protons in the nucleus also defines in large part the characteristics of an atom—is it a gas or a metal, for example. 

Two atoms with an identical number of protons in their nuclei belong to the same element. An element, like hydrogen, oxygen or iron, is a substance that cannot be broken down of a nuclear reaction—into anything else. In other words, one element cannot be transformed into another (again, with the except of nuclear reactions)