Parts of an Atom

Front

Atom Noun

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[at-uhm]

Back

Atom

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The smallest particle of an element that retains the element's properties, serving as the fundamental building block of all matter.

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Example: This diagram shows an atom's parts: a central nucleus with protons and neutrons, and electrons orbiting the nucleus in distinct energy shells.

Front

Nucleus Noun

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[noo-klee-uhs]

Back

Nucleus

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The dense, positively charged central core of an atom, containing protons and neutrons and making up nearly all its mass.

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Example: This diagram shows the nucleus, the central part of an atom, which contains a cluster of protons and neutrons.

Front

Proton Noun

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[proh-ton]

Back

Proton

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A stable subatomic particle with a positive electric charge, found within the atomic nucleus, which determines an element's identity.

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Example: This diagram shows a proton, a positively charged particle, located inside the nucleus of an atom along with neutral neutrons.

Front

Neutron Noun

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[noo-tron]

Back

Neutron

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A subatomic particle with no net electric charge (neutral) and a mass slightly larger than a proton, found in the nucleus.

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Example: This diagram shows a neutron (blue sphere) located inside the atom's central nucleus, along with protons, while electrons orbit the nucleus.

Front

Electron Noun

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[ih-lek-tron]

Back

Electron

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A stable subatomic particle with a negative electric charge that moves in the space surrounding the nucleus of an atom.

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Example: This diagram shows an electron as a particle that orbits the central nucleus of an atom, which also contains protons and neutrons.

Front

Ion Noun

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[ahy-on]

Back

Ion

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An atom or molecule that has a net electrical charge due to the loss or gain of one or more electrons.

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Example: A neutral sodium atom (Na) loses an electron, resulting in more protons than electrons and creating a positively charged sodium ion (Na¹⁺).

Front

Element Noun

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[el-uh-muhnt]

Back

Element

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A pure substance consisting only of atoms that all have the same number of protons in their atomic nuclei.

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Example: This diagram shows an atom of Oxygen, which is an example of an element. All Oxygen atoms have 8 protons, as shown by its atomic number.