Ions and Isotopes

Ions and Isotopes

Middle School

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Learning Objectives

• Identify the properties and locations of protons, neutrons, and electrons.

• Explain the difference between a neutral atom, an isotope, and an ion.

• Determine an atom's charge based on its number of protons and electrons.

• Understand how the number of neutrons creates different isotopes of an element.

Key Vocabulary

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Proton

A particle in the nucleus with a positive charge and a mass of one atomic mass unit.

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Neutron

A neutral particle found in the nucleus of an atom with a mass of one atomic unit.

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Electron

A low-mass particle with a negative charge that orbits an atom's nucleus in the electron cloud.

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Isotope

An atom with the same number of protons but a different number of neutrons than other atoms.

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Ion

An atom that has gained or lost electrons, resulting in an overall positive or negative charge.

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What's Inside an Atom?

• The center of an atom is the nucleus, containing protons and neutrons.

• Protons have a positive charge (+1) and a mass of about 1 amu.

• Electrons orbit the nucleus and have a negative charge (–1) and tiny mass.

• A neutral atom has an equal number of protons and electrons.

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Multiple Choice

Which subatomic particle has a positive charge and is located in the nucleus?

• Neutron

• Ion

• Proton

• Electron

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What are Isotopes?

• Isotopes are atoms of an element with different numbers of neutrons.

• They have the same number of protons, which defines the element.

• For example, all Beryllium atoms must have four protons in their nucleus.

• One Beryllium isotope has four neutrons, while another has three neutrons.

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Multiple Choice

An atom has 6 protons, 7 neutrons, and 6 electrons. Which of the following would be its isotope?

• An atom with 5 protons, 7 neutrons, and 6 electrons

• An atom with 7 protons, 7 neutrons, and 6 electrons

• An atom with 6 protons, 7 neutrons, and 7 electrons

• An atom with 6 protons, 8 neutrons, and 6 electrons

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What are Ions?

Positive Ions

• An ion with more protons than electrons has a positive electrical charge.

• These ions are created when a neutral atom loses one or more of its electrons.

• For example, an ion with 6 protons and 5 electrons has an overall charge of +1.

Negative Ions

• An ion with more electrons than protons has a negative electrical charge.

• These ions are created when a neutral atom gains one or more electrons.

• A Fluoride ion with 9 protons and 10 electrons has a charge of -1.

Multiple Choice

An atom has 17 protons and 18 electrons. What is its overall charge?

• 0

• -1

• +1

• -18

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Common Misconceptions About Atoms

Misconception	Correction
All atoms of the same element are identical.	Isotopes are atoms of an element with different numbers of neutrons.
Atoms are always electrically neutral.	Ions are atoms that have a positive or negative charge.
The number of neutrons determines the charge of an atom.	The charge is determined by the number of protons and electrons.

Multiple Choice

A scientist is studying two atoms. Atom A has 12 protons and 12 neutrons. Atom B has 12 protons and 13 neutrons. What is the relationship between these two atoms?

• They are different elements.

• They are isotopes of the same element.

• They are ions of the same element.

• They are a proton and a neutron.

Multiple Choice

How does a neutral magnesium atom (12 protons, 12 electrons) become a magnesium ion with a +2 charge?

• It loses 2 protons.

• It gains 2 protons.

• It loses 2 electrons.

• It gains 2 electrons.

Multiple Choice

An unknown particle has a positive charge and a mass of approximately 1 amu. Based on this evidence, what is the most likely identity of this particle?

• A proton

• An electron

• A neutron

• A negative ion

Multiple Choice

Analyze the following statement: 'An atom with 8 protons, 9 neutrons, and 10 electrons is a negative ion.' Why is this statement correct?

• Because it has more neutrons than protons, making it an isotope.

• Because it has more electrons than protons, resulting in a net negative charge.

• Because the number of protons is less than the number of electrons plus neutrons.

• Because the total number of particles (27) is an odd number.

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Summary

• The nucleus contains positively charged protons and neutral neutrons.

• Negatively charged electrons orbit the nucleus.

• Isotopes are atoms of the same element with a different number of neutrons.

• Ions are charged atoms that have an unequal number of protons and electrons.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4