The Periodic Table

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Atom Noun

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[at-uhm]

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Atom

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The basic building block of all matter, composed of a central nucleus surrounded by electrons.

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Example: This diagram shows an atom's structure: a central nucleus with protons and neutrons, surrounded by electrons orbiting in distinct shells.

Front

Proton Noun

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[proh-ton]

Back

Proton

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A subatomic particle with a positive electric charge that is found within the nucleus of an atom.

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Example: This diagram of an oxygen atom shows that a proton is a positively charged (+) particle located inside the central nucleus of an atom.

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 orbits the nucleus of an atom.

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Example: This Bohr model shows electrons (blue dots) orbiting the nucleus of a Sodium atom in distinct shells, with the numbers 2, 8, and 1 indicating the electron count in each shell.

Front

Neutron Noun

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[noo-tron]

Back

Neutron

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A subatomic particle with no electric charge, found in the nucleus of an atom alongside protons.

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Example: This diagram shows a neutron, a particle with no charge, located inside the atom's central core, the nucleus, along with protons.

Front

Nucleus Noun

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[noo-klee-uhs]

Back

Nucleus

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The dense, positively charged center of an atom, which is composed of protons and neutrons.

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Example: This diagram shows the nucleus is the dense center of an atom, containing protons and neutrons, with electrons orbiting in outer shells.

Front

Atomic Number Noun

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[uh-tom-ik nuhm-ber]

Back

Atomic Number

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The number of protons in an atom's nucleus, which uniquely identifies a chemical element.

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Example: This diagram of an Oxygen atom shows its atomic number is 8. The atomic number tells you the number of protons in an atom's nucleus.

Front

Atomic Mass Noun

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[uh-tom-ik mas]

Back

Atomic Mass

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The total mass of an atom, approximately equal to the sum of its protons and neutrons.

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Example: This diagram shows that the mass number (4) of a helium atom is the total count of its protons (red) and neutrons (white) in the nucleus.

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Element Noun

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[el-uh-muhnt]

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Element

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A pure substance consisting of only one type of atom, distinguished by its specific atomic number.

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Example: This image shows how an element, like Carbon, is represented on the periodic table with its unique atomic number, symbol, name, and atomic mass.

Front

Chemical Symbol Noun

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[kem-i-kuhl sim-buhl]

Back

Chemical Symbol

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A one or two-letter abbreviation used to represent a specific chemical element on the periodic table.

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Example: This image shows a tile for the element Gold from the periodic table, where 'Au' is the chemical symbol, a one or two-letter abbreviation.

Front

Periodic Table Noun

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[peer-ee-od-ik tey-buhl]

Back

Periodic Table

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A tabular arrangement of chemical elements ordered by atomic number, showing periodic trends in their properties.

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Example: This image shows the periodic table, a chart organizing all known chemical elements. A key explains how to read each element's box, showing its atomic number, symbol, name, and atomic mass.