Atoms, Molecules, pH, and Reactions Lecture Quiz

1. The three basic components of an atom are:

Protons, neutrons, and electrons

2. An element is determined by the number of:

Protons

3. The nucleus of an atom consists of:

Protons and neutrons

4. A single proton has what electrical charge?

Positive charge

5. Which particles have approximately the same size and mass as each other?

Protons and neutrons

6. Which two particles would be attracted to each other?

Electrons and protons

7. The atomic number of an atom is:

The number of protons

8. Changing the number of neutrons of an atom changes:

It to an isotope

9. The smallest unit of matter that can enter chemical reactions and is indivisible by chemical means:

Atom

10. Atomic mass is the number of:

Protons plus neutrons

11. Chlorine has an atomic number of 17. How many electrons are in its outermost shell?

7

12. K⁺Cl⁻ is held together by what type of bond?

Ionic bond

13. Which type of bond shares electrons between atoms?

Covalent bond

14. HCl + NaOH produces:

NaCl + H₂O

15. Many water molecules are weakly held together by:

Hydrogen bonds

16. Which statement about water is NOT true?

Because of hydrogen bonding, liquid water is less dense than ice

17. Which substances release hydrogen ions (H⁺) in water?

Acids

18. What is the pH of a neutral solution?

pH 7

19. What helps maintain a relatively constant pH by taking up excess H⁺ or OH⁻?

Buffers

20. The main elements found in organic molecules are:

Carbon and hydrogen

21. An atom of potassium (K) has an atomic number of 19 and a mass number of 39. How many neutrons does it have?

20 neutrons

22. CH4 + 2 O2 → _____ + 2 H2O. What molecule balances the equation?

CO2

23. A beaker full of acid is added to a beaker full of base. The pH of the base will:

Decrease

24. What element has 2 electrons in the first shell and 5 electrons in the second shell?

Nitrogen

25. Changing the number of neutrons of an atom changes its:

Isotope

26. Which two particles would be attracted to each other?

Electrons and protons

27. The nucleus of an atom, which gives the majority of the mass number, consists of:

Protons and neutrons

28. An element is determined by the number of:

Protons

29. Sharing electrons between hydrogen and oxygen to form water creates what type of bond?

Covalent bond

30. In potassium chloride, chlorine accepts an electron donated by potassium. What kind of bond develops?

Ionic bond