Composition of Matter and Isotopes – Lecture Notes Review

A set of Q&A flashcards covering matter, elements, atoms, isotopes, compounds, and basic chemical reactions from the notes.

What is matter?

Anything that occupies space and has mass.

What is mass?

The quantity of matter an object has.

What is an element?

A pure substance that cannot be broken down into simpler substances.

Approximately how many elements are important to life?

About 30.

Which six elements are considered the most important for life?

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur (C, H, O, N, P, S).

What are the next six most important elements for life after CHONPS?

Sodium (Na), Magnesium (Mg), Chlorine (Cl), Potassium (K), Calcium (Ca), Iron (Fe).

What is the nucleus in an atom?

The central core of the atom.

Which subatomic particle carries a positive charge?

A proton.

What does the atomic number represent?

The number of protons in an atom.

What is a neutron?

A subatomic particle with no electric charge.

What is an electron?

A negatively charged subatomic particle that orbits the nucleus.

What are energy levels in atoms?

The arranged electron shells surrounding the nucleus where electrons reside.

How many electrons can fit in the first energy level?

2 electrons.

How many electrons can fit in the second energy level?

8 electrons.

How many electrons can fit in the third energy level?

8 electrons.

What does the atomic number indicate?

The number of protons in the atom.

What is the mass number?

The total number of protons and neutrons in the nucleus.

The difference between the mass number and the atomic number equals the number of what?

Neutrons.

For phosphorus-31 (31P), how many protons are there?

15 protons.

For phosphorus-31, how many electrons are present (assuming a neutral atom)?

15 electrons.

For phosphorus-31, how many neutrons are present?

16 neutrons.

What is an isotope?

Atoms of the same element with the same number of protons but a different number of neutrons, leading to different masses.

Do isotopes of the same element have the same chemical behavior?

Yes, isotopes behave chemically the same.

What varies among isotopes?

The number of neutrons.

Are all isotopes stable?

No; some are radioactive and decay spontaneously.

What is the most common carbon isotope?

Carbon-12 (12C).

Name two other carbon isotopes.

Carbon-13 (13C) and Carbon-14 (14C).

What is the use of radioactive isotopes in medicine and research?

They can function as markers for their nonradioactive counterparts.

Name a radioactive hydrogen isotope.

Hydrogen-3 (tritium).

What is a compound?

A substance made of two or more elements.

What happens during a chemical reaction?

Chemical bonds are broken, atoms are rearranged, and new chemical bonds are formed.

In the reaction 2H2 + O2 → 2H2O, which are the reactants and which are the products?

Reactants: H2 and O2; Products: H2O.

In the reaction 6CO2 + 6H2O → C6H12O6 + 6O2, identify the reactants and products.

Reactants: CO2 and H2O; Products: C6H12O6 and O2.

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