What is an Atom?

Atom

"The Atom"

What is an Atom?
What is an atom? Everything that takes up space called Matter (see States of Matter). Matter has weight, volume and mass. Matter is made up of tiny building blocks called Atoms. Atoms are tiny – at least 100 times smaller than the width of a human hair. The purest type of atom is called an element. Different types of atoms are called chemical elements, such as the Element Neon or the Element Gold. The exact size of the atom changes, depending on the element, see the Element Examples above.

What is an Atom? The Nucleus of an Atom
The nucleus is in the middle of the atom and contains protons, neutrons and electrons. These smaller particles of the atom - the protons, neutrons and electrons - all have different properties. Atoms must have equal numbers of protons and electrons.

What is an Atom? - An Atom determines an Element
Atoms are composed of three kinds of smaller particles, called protons, neutrons and electrons. Protons and neutrons are made up of even smaller particles called quarks. The number of protons, the number of neutrons and the number of electrons an atom has determines what the element it is.

Atoms are composed of 3 kinds of small particles: protons, neutrons and electrons
Atoms must have equal numbers of protons and electrons

What is an Atom? Protons
Atoms of a particular element contain the same number of protons. Protons are much larger and heavier than electrons and have a positive charge. Protons are positively charged and located in the nucleus together with the neutrons.

What is an Atom? Electrons
Atoms of a particular element contain the same number of electrons. Electrons are tiny, very light particles that have a negative electrical charge. Electrons are negatively charged, circling the nucleus, making it a neutral, orbital particle.

What is an Atom? - Neutrons?
Neutrons are large and heavy like protons, however neutrons have no electrical charge.

What is an Atom? - Protons, Electrons and Neutrons
Atoms are composed of 3 kinds of small particles: protons, neutrons and electrons.

Protons have a positive charge
Electrons have a negative charge
Neutrons have no electrical charge

Protons, Electrons and Neutrons

Particle: Proton Charge: +1 Location: Nucleus of Atom
Particle: Electron Charge: -1 Location: Orbital
Particle: Neutron Charge: 0 Location: Nucleus of Atom

The Atomic number = The Number of Protons in the atom of an element
Atoms must have equal numbers of protons and electrons

What is an Atom? - Molecules and Atoms
Molecules and Atoms. A molecule is the smallest amount of a chemical substance that can exist. A molecule is capable of independent existence and can consist of one or more atoms, see the Molecules & Atoms link at the top of the page.

What is an Atom? Related Terms
The Atomic Number is the number of protons in the atom, see Periodic Table Number. The Atomic Mass, or atomic weight, is the average mass of atoms (protons and neutrons) of an element, see . Atoms of an element that have differing numbers of neutrons (but a constant atomic number) are termed isotopes. Element Isotopes have the same number of protons (and electrons) but different numbers of neutrons in the atom of an element.