Handout Part 1

Question 1

Electrons move around the nucleus in _________________________ called ______________.

Answer 1

circular orbits, shells

Question 2

Each electron shell is _______________________ (__). __________________________________ is given the number of 1 (i.e. __ = 1).

Answer 2

given a number (n); The shell nearest to the nucleus; n

Question 3

How many electrons can electron shell n hold?

Answer 3

2n^2.

Question 4

Describe how electrons fill their shells.

Answer 4

They start with the innermost shell and work outwards as each shell is fully filled.

Question 5

What is the use of an electron diagram? Apart from this type of diagram, how else can we show the arrangements of electrons? What is an advantage of this alternative way?

Answer 5

We can show the arrangements of electrons in an atom by using one.
We can do so by writing down its electronic arrangement/ electron configuration.
We can save the time needed to draw atoms.

Question 6

Name two exceptions in which electrons are filled in the next shell even when the previous shell isn’t fully filled, and their electronic arrangements.

Answer 6

Calcium — 2, 8, 8, 2

Potassium — 2, 8, 8, 1

Question 7

What increases in elements across a horizontal period?

Answer 7

The number of electrons in atoms.

Question 8

period number of an element = ______________________________________________________________

Answer 8

the number of occupied electron shells in an atom of the element

Question 9

group number of an element = _________________________________________________________________

Answer 9

the number of outermost shell electrons in an atom of the element