Atomic Structure and Isotopes

Question-and-answer flashcards covering subatomic particles, atomic and mass numbers, ions, and isotopes with examples.

What are the three sub-atomic particles that make up an atom?

Protons, neutrons, and electrons.

What are the relative mass and relative charge of a proton?

Relative mass = 1; relative charge = +1.

What are the relative mass and relative charge of a neutron?

Relative mass = 1; relative charge = 0.

What are the relative mass and relative charge of an electron?

Relative mass ≈ 1⁄2000; relative charge = –1.

Where are protons, neutrons, and electrons located within an atom?

Protons and neutrons are in the nucleus, while electrons orbit the nucleus in shells.

What does the atomic number (Z) represent?

The number of protons in an atom, which identifies the element.

What does the mass number (A) represent?

The total number of protons and neutrons in an atom.

How do you calculate the number of neutrons in an atom?

Number of neutrons = Mass number – Atomic number.

What is an ion and how is it formed?

An ion is an atom that has gained or lost electrons. Losing electrons forms a positive ion (cation); gaining electrons forms a negative ion (anion).

Provide an example of a negative ion and state its charge.

Br⁻: 36 electrons and 35 protons, giving a –1 charge.

Provide an example of a positive ion and state its charge.

Mg²⁺: 10 electrons and 12 protons, giving a +2 charge.

What are isotopes?

Atoms of the same element with the same number of protons but different numbers of neutrons.

Give two naturally occurring isotopes of chlorine with their neutron counts.

Chlorine-35: 17 protons, 18 neutrons; Chlorine-37: 17 protons, 20 neutrons.

List three isotopes of magnesium and their neutron numbers.

Mg-24: 12 neutrons; Mg-25: 13 neutrons; Mg-26: 14 neutrons.

Do isotopes differ in chemical properties? Explain.

No. Isotopes have the same chemical properties because they possess the same number of electrons, though their physical properties (e.g., density, diffusion rate) may vary.