The Modern Atomic Theory

Question 1

An atom of sodium-23 (Na-23) has a net charge of +1. Identify the number of protons, neutrons, and electrons in the atom. Then, explain how you determined the number of each type of particle. Use the periodic table to help you.

Revolt · Accepted Answer

Sodium-23 has 11 protons, 12 neutrons, and 10 electrons. The atomic number gives the number of protons (11). The number of neutrons is found by subtracting the atomic number from the mass number: 23 − 11 = 12. Because each proton has a +1 charge and each electron has a −1 charge, a +1 net charge means the atom has one fewer electron than protons: 11 − 1 = 10 electrons.

Question 2

amu

Revolt · Accepted Answer

11.01

Question 3

Using the information in the table to the right, calculate the average atomic mass of strontium. Report to two decimal places. amu

Revolt · Accepted Answer

87.62

Question 4

Your answer should include all the following pieces of information. Check off each of the items you included in your answer.

Revolt · Accepted Answer

It contains 11 protons in the nucleus.; It contains 12 neutrons in the nucleus.; It contains 10 electrons surrounding the nucleus.; The number of electrons are calculated from net charge and charge of proton (+1) and electron (–1).; 12 neutrons are calculated from atomic number: 11 and mass number: 23.

The Modern Atomic Theory Answers

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