Electrons & the Value of Valence E to EVERYTHING chemistry!

State the number of valence electrons in an atom of sulfur-32 in the ground state

• 16

• 6

• 8

• 10

Answer explanation

Group VI or 16, 6 valence electrons

2-8-6

[Ne] 3s²3p⁴

Tags

NGSS.HS-PS1-1

Which of the following are accurate and equivalent electronic configurations for an atom of sulfur in the ground state?

• 2-8-6

  [Ne] 3s²3p⁴

• 2-6-8

  [Ne] 3s²3p⁶

• 2-8-8

  [Ar]

• 2-6-8

  [Ne] 3s²3p⁴

Tags

NGSS.HS-PS1-1

Which of the following are correct representations of the electronic configuration of the sulfide anion, S^2-?

• 1s²2s²2p⁶3s²3p⁶

  [Ar]

• 1s²2s²2p⁶3s²3p⁴

  [Ne] 3s²3p⁴

• 1s²2s²2p⁶3s²3p⁵4s¹

  [Ar]

• 1s²2s²2p⁶3s²3p⁴4s²

  [Ne]3s²3p⁴4s²

Answer explanation

For anions you are adding electrons

the 3s²3p⁶ shows 8 valence electrons = noble gas configuration

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which of the following include two correct and equivalent electronic configurations for oxide anion, O^2-?

• 1s²2s²2p⁶

  [Ne]

• 1s²2s²2p⁴3s²

  [Ne]

• 1s²2s²2p⁵3s¹

  [He]2s²2p⁵3s¹

• 1s²2s²2p⁴

  [He]2s²2p⁴

Answer explanation

the pink answer represents regular oxygen atom with 6 valence electrons. You can follow the usual rules as below, just remember you have to add in 2 valence electrons because it's an ANION.

1. 1. break the periodic table up in blocks

2. 2. number the periods

3. 3: Find the element on the PT:

4. a. Start at the top left and go across left to right through each row until you reach the element needed.

5. b. As you move past squares, write out the electron configuration.

6. c. Ex: as you go though the first row, you will get 1s².

7. 1 = row #

8. s = name of the block

9. superscript 2 = how far into the block you are to get to that element; the number of squares in the block you are getting through.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which of the following contain TWO correct representations of the electronic configuration of an atom of the element oxygen?

• 1s²2s²2p²

  [He]2s²2p²

• 1s²2s²2p⁶

  [Ar]

• 1s²2s²2p⁴

  [He]2s²2p⁴

• 1s²2s²2p⁴

  [He]2p⁴

Answer explanation

1. 1. break the periodic table up in blocks

2. 2. number the periods

3. 3: Find the element on the PT:

4. a. Start at the top left and go across left to right through each row until you reach the element needed.

5. b. As you move past squares, write out the electron configuration.

6. c. Ex: as you go though the first row, you will get 1s².

7. 1 = row #

8. s = name of the block

9. superscript 2 = how far into the block you are to get to that element; the number of squares in the block you are getting through.

Tags

NGSS.HS-PS1-1

33. Which subatomic particles were discovered as the result of experiments with cathode ray tubes?

• positrons

• electrons

• protons

• neutrons

Answer explanation

beam or ray from cathode went to the positively charged plate

since opposites attract, if the beam went to the + plate, JJ Tompson deduced it must contain NEGATIVELY charged particles....

Tags

NGSS.HS-PS2-5

33. As the atomic number increases in Group 2 from Be to Ba, the first ionization energy

Hint :if atomic number is going up and we're in a group, we must be going DOWN A GROUP

• 0. decreases, and the atomic radius decreases

• 0. increases, and the atomic radius decreases

• 0. increases, and the atomic radius increases

• 0. decreases, and the atomic radius increases

Answer explanation

larger atomic radius

valence e- are far far away from the nucleus

nucleus' effective charge is weak because of:

-large distance between nucleus and far-away valence electrons

-shielding: repelling forces emitted by core electrons that make the valence electrons want to get as far away from atom as possible

low ie = little energy needed to remove valence e-

easy to remove energy

little effort to remove e-

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

33. Which change in electron location in an atom of calcium is accompanied by the greatest amount of energy emitted?

• 0. from shell 1 to shell 2

• 0. from shell 2 to shell 1

• 0. from shell 1 to shell 4

• 0. from shell 4 to shell 1

Answer explanation

emitted: energy released, electron moving down energy levels

bigger the transition in energy shells (moving several energy levels down vs only moving 1 or energy levels down) gives off more energy.

Example of this principle is featured in the diagram:

blue-violet light (c) spanning the biggest transition downward has shortest wavelength thus has the most energy

also see how a + b = c

Tags

NGSS.HS-PS1-4

What is represented in diagram 2?

• a positive ion of hydrogen

• a negative ion of hydrogen

• an atom of hydrogen in an excited state

• an atom of hydrogen in the ground state

Answer explanation

In the ground state, a hydrogen atom has 1 energy shell (period 1) and one electron

(it has 1 proton so we need 1 electron to keep the atom neutral)

According to Aufbau, lowest orbitals are filled first so the 1s orbital should be filled with hydrogen's one electron...it's not, that electron is all the way up in higher energy land!

11. Which atom forms an ion with a radius larger than the atomic radius?

• calcium atom

• oxygen atom

• lead atom

• tin atom

Answer explanation

oxygen gains two electrons so it's ionic radius is bigger than its atomic radius

<-- see visual for examples of this principle

ionic radius = radius of the ion an atom forms