Chemistry 101 - Basic Concepts

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

Electrons Elements Protons and neutrons Molecules

2. What does the atomic number represent?

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

3. Which subatomic particle has no charge?

Neutron Nucleus Proton Electron

4. Which particle has a positive charge?

Electron Neutron Atom Proton

5. What is the charge of a neutron?

+1 0 (neutral) Depends on isotope -1

6. What is a molecule?

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

7. What do protons and neutrons help identify?

Electrons Elements Molecules Different atoms and isotopes

8. Which particle is found outside the nucleus?

Neutron Electron Proton Nucleus

9. Isotopes differ in their number of:

Electrons Neutrons Protons Atoms

10. Which particle has a negative charge?

Proton Atom Electron Neutron

11. Which of the following is an element?

Salt Carbon dioxide Water Oxygen

12. What is the smallest unit of matter?

Compound Element Molecule Atom

13. What is the chemical formula for table salt?

CO2 NaCl H2O O2

14. What is the chemical formula for water?

CO2 O2 H2O NaCl

15. Which of the following is a pure substance?

Mixture Molecule Compound Element

16. What is the mass number?

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

17. What is the charge of a proton?

+2 0 +1 -1

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

Liquid Solid Plasma Light

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

Neutron Atom Electron Proton

20. Atoms are made up of:

Elements Subatomic particles Molecules Compounds