Atoms and Periodic Table – Answers to Practice Questions

1) Complete the following sentences, using the words below. Each word can be used once, more than once, or not at all.

 All substances are made from atoms . There are 92 pure substances that are made from atoms of only one type, and these we call elements. Most pure substances are made from atoms of more than one type chemically bonded together. These are called compounds. Some substances will dissolve in water to form mixtures called solutions.

 

2) Decide whether the following are true or false:

            The lightest subatomic particles are found in the nucleus  FALSE

            The positively charged particles are found in the nucleus  TRUE

            Protons have and positive charge and neutrons a negative charge  FALSE

            Protons and neutrons have the same mass  TRUE

 

3) An atom has a mass number of 21 and 10 electrons. Determine how many protons and neutrons this atom has.   It has 11 neutrons and 10 protons

 

4) An atom has an atomic number of 6 and mass number of 13. What can you say about the number of protons, neutrons and electrons in this atom?   6 protons, 6 electrons, 7 neutrons

 

5) A sample of the element boron is found to contain 20% of the isotope 10B and 80% of the isotope 11B. Calculate the relative atomic mass of this sample of boron.  relative atomic mass = (0.2 x 10) + (0.8 x 11)  = 10.8 

 

6) Identify the following atoms:

In Group 3, has 2 electron shells  boron

In Period 3, has 6 outer shell electrons  sulphur

In Group 5, has 7 electrons   nitrogen

Has 18 electrons  argon

Has 3 shells containing electrons, and 2 electrons in the outer shell  magnesium

 

7) How many outer shell electrons does the element selenium have in its outer shell?  6

 

8) Bismuth is an element in Group 5. Explain how tests of its physical properties might allow you to determine whether bismuth is a metal or a non-metal.  Its appearance will be shiny (when cut) if it is a metal and dull if it is a non-metal. It will conduct electricity if a metal and not if it is a non-metal.

 

9) French scientist Antoine Lavoisier was experimenting with an element he called azote. Explain how tests of its chemical properties would help to determine whether azote was a metal or a non-metal.  If azote is reacted with oxygen to make an oxide, and the oxide is dissolved in water, the resulting solution will be alkaline if azote is a metal and acidic if azote is a non-metal.

 

10) In 2016 names were given to the elements with atomic numbers 113. 115, 117 and 118. Element 118 is a member of Group 8/0 – the Noble Gases. It has been named Oganesson. Using your knowledge of the Noble Gases, predict what the chemical and physical properties of Oganesson will be.  It will be an unreactive colourless gas with high density.