Atomic Structure Worksheet

02-04 Atomic Structure – Questions
Name: ____________________________
1. The extremely low-mass, negatively charged particle found outside the nucleus is
called an __________.
2. The number of protons in the nucleus of the atom is indicated by the _________
3. The symbol for an element is either a _________ letter or possibly a
__________ letter followed by a ______________ letter.
4. Atoms of the same element that differ in their number of neutrons in the nucleus
are called ____________________.
5. The total number of nucleons (particles in the nucleus) in the atom make up the
__________ number.
6. A neutral nuclear particle having a mass of about 1 AMU is called the
7. The ___________ is a positively charged nuclear particle with a mass of about 1
8. The _____________ is the small, positively charged center of the atom.
9. In a neutral atom, the number of protons in the nucleus equals the number of
_____________ outside the nucleus.
10. An element’s atomic number is (different from, the same as) that of any other
11. The ____________ number identifies the specific element.
12. The neutron and the proton have nearly the same mass, which is about 1840 times
more massive than the ____________.
13. More than 99% of the mass of the atom is concentrated in the (nucleus, electron
14. The AMU or ______________________ is the basic unit of atomic mass and it is
equal to _________the mass of the carbon-12 atom.
15. The total number of protons and neutrons in an atom is called the ___________
16. Isotopes are atoms that have the same number of __________, but different
numbers of_______________.
17. U-234 and U-238 represent ______________ of the same element.
18. Na-24 and Mg-24 represent ______________ of two different elements.
19. The charge of one proton balances the charge of one ______________.
20. The protons and neutrons present in the nucleus are collectively called
__________. (Hint – see number 5 above.)
21. Atoms that have the same number of protons, but a different number of
____________ are called isotopes.
02-04 Atomic Structure – Questions
Name: ____________________________
22. Two nuclei with the same number of protons, but different mass numbers are
referred to as _______________________.
23. Uranium is known to have 143 neutrons. What is its mass number? _______
24. An isotope of this element (Uranium) has 146 neutrons. What is that isotope’s mass
number? ________
25. Which of these has the largest number of neutrons per atom?
a. Bi-210
b. Po-210
c. At-210
d. At-211
26. Identify whether each of these pairs is an isotope of each other or not:
a. Lu-154 and Lu-161
b. Yb-167 and Lu-167
c. Two atoms, both with atomic number = 84 and mass number = 204
d. Two atoms, one with atomic number = 53 and mass number = 133; the other
with atomic number = 53 and mass number = 137
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