Question

activity b: electron arrangements
get the gizmo ready: * create a neutral hydrogen atom (1 proton, 0 neutrons, 1 electron).
question: how are electrons arranged around the nucleus of an atom?

1. observe: add electrons to the atom until you have used all the available electrons. how are the electrons arranged?
2. analyze: electrons are arranged in orbits called energy levels. the gizmo shows all of the first two energy levels but only part of the third energy level.

a. how many electrons can fit in the first energy level?
b. how many electrons can fit in the second energy level?
c. how many electrons fit in the part of the third energy level shown?

1. observe: click reset (?). the electrons in the outermost orbit, called valence electrons, help to create chemical bonds. create a lithium atom (3 protons, 4 neutrons, 3 electrons).

how many valence electrons are in a neutral lithium atom?

1. diagram: turn on show electron dot diagram. the valence electrons of an atom are shown in an electron dot diagram. each dot represents a valence electron.

draw the electron dot diagram for neutral lithium:

1. practice: turn off show electron dot diagram. use the gizmo to create a neutral atom of each of the following elements. draw an electron dot diagram for each. when you are finished, turn on show electron dot diagram and check your answers.

h he li be b c n
o f ne na mg al si
extend your thinking: many chemical properties are determined by the number of valence electrons. elements with the same number of valence electrons will have similar properties.
which element has similar properties to lithium? beryllium?
explain:

Explanation:

Step1: Recall electron - shell capacity rules

The first energy level can hold a maximum of 2 electrons.

Step2: Recall second - energy - level capacity

The second energy level can hold a maximum of 8 electrons.

Step3: Analyze the part of the third energy level shown

The part of the third energy level shown in the Gizmo can hold 8 electrons.

Step4: Determine valence electrons in lithium

A lithium atom has 3 electrons. The first energy level takes 2 electrons, and the remaining 1 electron is in the second energy level. So, a neutral lithium atom has 1 valence electron.

Step5: Draw electron - dot diagram for lithium

The electron - dot diagram for lithium has 1 dot representing the valence electron.

Step6: Elements with similar properties to lithium

Elements in the same group of the periodic table have similar properties. Lithium is in Group 1. Sodium (Na) is also in Group 1, so it has similar properties to lithium. Beryllium is in Group 2, so it does not have similar properties to lithium.

Answer:

1. Electrons are arranged in energy levels around the nucleus.
2. A. 2

B. 8
C. 8

1. 1
2. One dot around the symbol Li.
3. For H: One dot around the symbol H. For He: Two dots around the symbol He. For Li: One dot around the symbol Li. For Be: Two dots around the symbol Be. For B: Three dots around the symbol B. For C: Four dots around the symbol C. For N: Five dots around the symbol N. For O: Six dots around the symbol O. For F: Seven dots around the symbol F. For Ne: Eight dots around the symbol Ne. For Na: One dot around the symbol Na. For Mg: Two dots around the symbol Mg. For Al: Three dots around the symbol Al. For Si: Four dots around the symbol Si.

Extend your thinking: Sodium (Na) has similar properties to lithium. Beryllium does not have similar properties to lithium because lithium is in Group 1 with 1 valence electron and Beryllium is in Group 2 with 2 valence electrons, and elements with the same number of valence electrons have similar properties.