Chemistry 101 - Basic Concepts

1. What is the smallest unit of matter?

Compound Atom Element Molecule

2. What is the mass number?

Number of protons Number of electrons Total number of protons and neutrons Atomic number

3. What do protons and neutrons help identify?

Elements Different atoms and isotopes Electrons Molecules

4. What is a molecule?

A single atom An element A pure substance Two or more atoms chemically bonded

5. What is the charge of a proton?

+2 +1 0 -1

6. What is the charge of a neutron?

Depends on isotope 0 (neutral) +1 -1

7. Isotopes differ in their number of:

Protons Neutrons Atoms Electrons

8. Which particle is found outside the nucleus?

Electron Proton Neutron Nucleus

9. Which particle has a positive charge?

Neutron Proton Electron Atom

10. Which of the following is a pure substance?

Mixture Molecule Element Compound

11. Which subatomic particle has no charge?

Electron Nucleus Proton Neutron

12. Which particle has a negative charge?

Electron Atom Proton Neutron

13. What is the chemical formula for table salt?

NaCl O2 H2O CO2

14. Which of the following is NOT a subatomic particle?

Electron Atom Proton Neutron

15. What is the main component of an atom’s nucleus?

Elements Electrons Protons and neutrons Molecules

16. What is the chemical formula for water?

H2O CO2 NaCl O2

17. Atoms are made up of:

Compounds Molecules Subatomic particles Elements

18. Which of the following is NOT a state of matter?

Light Solid Liquid Plasma

19. What does the atomic number represent?

Number of protons in the nucleus Mass of the atom Number of electrons Number of neutrons

20. Which of the following is an element?

Carbon dioxide Water Salt Oxygen