Topic 4 - The Periodic Table

Question 1

1.13 - Describe how Mendeleev arranged the periodic table

Answer 1

Elements were arranged in order of increasing relative atomic masses and left gaps where an element was undiscovered.
If elements had similar chemical and physical properties, these elements were closer.
An example is Tellerium and Group 7 metals, as G7 non-metals don’t react with oxygen easily but Tellerium metal does react with oxygen. Tellerium has a lower RAM than Iodine so should be before it in the table, but as the non-metals had similar chemical properties they were placed together.
Vertical rows had elements with increasing RAM and horizontal rows were similar in chemical properties.

Question 2

1.14 - Describe how Mendeleev used his table to predict properties of some elements

Answer 2

He used the properties of elements nearby the undiscovered element to predict their properties such as RAM, density, melting point and how it reacts.

Question 3

1.15 - Explain why Mendeleev didn’t arrange the table correctly with increasing RAM

Answer 3

Because the relative atomic mass did not account for the isotopes, this meant that some elements would’ve had higher RAM if the isotopes were taken into account but a lower RAM if an isotope was measured instead of the actual element.

Question 4

1.16 - Explain the meaning of atomic number

Answer 4

Atomic number is the number of protons.
Elements are arranged in order of increasing atomic number, elements in a group have the same electrons in their outer shell which means they have the same amount of protons giving similar chemical properties.

Question 5

1.17 - How are elements arranged in the modern periodic table?

Answer 5

Elements in a row or period are arranged in order of increasing atomic number.
Elements with similar properties are place in the same column or group.
Non-metals are on the right of the table.

Question 6

1.18 - How can you identify a metal or a non-metal according to their position in the periodic table?

Answer 6

Metals are elements that form positive ions. They are found to the left as they lose electrons to form a stable structure meaning they will have a lower group number.
Non-metals don’t form positive ions and found on the right of the periodic table, as they gain electrons to form a stable structure meaning they will have a higher group number.

Question 7

1.19 - What are the electronic configurations of the first 20 elements in the periodic table?

Answer 7

First shell contains up to 2 atoms, second and third shells contain up to 8 electron.
For Na the configuration is 2.8.1.

Question 8

1.20 - How is the electronic configuration of an element related to its position in the periodic table?

Answer 8

Number of occupied shells is the period number or row. ( F has 2 shells and is in second period )
Number of electrons in the outer shell is its group number or column. ( C has 4 outer electrons so is in fourth group )