History of Periodic Table

Question 1

What are groups?
What do they tell you?

Answer 1

• Columns on periodic table
• How many electrons there are on outermost shell

Question 2

What are periods?
What do they tell you?

Answer 2

• Rows on periodic table
• How many electron shells there are.

Question 3

What were the features of Newland’s periodic table?

Answer 3

• Order of atomic weight
• Law of octaves, noticed that each 8th element had similar properties.

Question 4

What are the problems with Newland’s periodic table?

Answer 4

• Elements with different properties in same group.
• Metals + non metals in same group
• Only stuck to putting it in increasing atomic weight.

Question 5

What were the features of Mendeleev’s periodic table?

Answer 5

• Order of atomic weight
• Groups had similar properties
• Left gaps for undiscovered elements
• Predicted properties of undiscovered elements

Question 6

What is the modern periodic table arranged in?

Answer 6

• Increasing atomic number
• Groups based on properties

Question 7

Why were elements arranged in atomic weight, not atomic mass?

Answer 7

• Atomic mass is the number of protons+ neutrons
• Subatomic particles weren’t discovered

Question 8

How did the discovery of isotopes prove that Mendeleev was right not to order his periodic table in order of atomic weight?

Answer 8

• The weight of an atom doesn’t predict it’s chemical properties.
• IT is the proton number.

Question 9

Give 2 differences in the modern periodic table to Mendeleev’s periodic table.

Answer 9

• Order of atomic number
• Group 0 discovered

Question 10

Describe 2 changes that Mendeleev made to early periodic tables.

Answer 10

• He left gaps/ predicted properties of undiscovered elements
• Put elements in groups with similar properties

Question 11

How are elements in the periodic table arranged?

Answer 11

1.) Order of atomic number
2.) Elements with similar properties are in columns, known as groups.

Question 12

Why do elements in the same group of PT have similar chemical properties?

Answer 12

• Have the same number of electrons on outer shell so have similar chemical properties.

Question 13

What is the difference between atomic weight and atomic mass?

Answer 13

• They are the exact same thing.
• BUT: atomic weight wouldn’t have been looking at protons + neutrons. They just new there were atoms that were causing a mass.