Unit 4: Electrons in Atoms

Question 1

Why wasn’t Rutherford’s atomic model effective?

Answer 1

It didn’t explain chemical properties, which depend on electrons in atoms. It was too simple because it just showed the electrons flying around the nucleus.

Question 2

When did Niels Bohr propose his model?

Answer 2

1913

Question 3

What atom did Bohr look at to design his model?

Answer 3

The simplest atom, Hydrogen

Question 4

How are electrons organized in the Bohr model?

Answer 4

Electrons move around the nucleus in fixed orbits. Each orbit has its own energy level, like rungs on a ladder. The path of an electron is similar to that of a large moving object.

Question 5

When atoms absorb or emit light…

Answer 5

Their energy changes
Absorb= electrons move to a higher level
Emit= when electrons drop back down a level

Question 6

The further an energy level is from the nucleus, the _____ the energy

Answer 6

Higher

Question 7

Higher energy levels are ______ together

Answer 7

Closer

Question 8

Define quantum

Answer 8

The amount of energy needed to move electrons one energy level

Question 9

It takes ____ energy to change levels higher up because…

Answer 9

Less

The electrons were farther away from the positive nucleus attracting it

Question 10

What is the relationship between electrons, quantums, and energy levels?

Answer 10

Electrons receive a quantum to go up a level. Electrons release a quantum to go down.

Question 11

What was wrong about the Bohr model?

Answer 11

The model only agreed with Hydrogen. It didn’t explain energy absorbed or given off by atoms with more electrons.

Question 12

When did Schrodinger propose his model?

Answer 12

1926

Question 13

Schrodinger wrote a ______ to describe __________.

Answer 13

Mathematical equation

The behavior of electrons in hydrogen

Question 14

What is the quantum mechanical model?

Answer 14

Modern description of electrons in atoms that determines the allowed energy (orbit) an electron can have and uses these possible “allowed” energies to figure out the probability of finding the electron in different locations around the nucleus.

Question 15

What is the electron cloud?

Answer 15

Possible locations of electrons because you can’t find the exact location of an electron at any one instant. The cloud is more areas where the electron is more likely to be.

Question 16

Electrons clouds are areas where the electron is what percent of the time?

Answer 16

90%

Question 17

Describe the development of the atomic model from Rutherford through Schrodinger.

Answer 17

Rutherford’s model first showed the nucleus, but it’s description of electrons was too simple because it didn’t explain how chemical properties depend on electrons. Bohr’s model attempted to explain this by placing electrons in fixed orbits at different energy levels, but it didn’t work for atoms with more than one electron and the orbits weren’t an accurate representation. Schrodinger’s model showed the more accurate possible locations of electrons because a fixed orbit can’t actually be calculated.

Question 18

Define electron configuration.

Answer 18

The arrangement of electrons in orbitals around the nucleus.

Question 19

What is the Aufbau principle?

Answer 19

Electrons occupy orbitals of the lowest energy first.

Question 20

What is the Pauli Exclusion Principle?

Answer 20

Maximum of 2 electrons in each orbital and the electrons must have opposite spins.

Question 21

What is Hund’s Rule?

Answer 21

1 electron occupies each orbital until entire sunk even is filled with electrons with the same spin. Then the orbitals can be filled with a second electron of the opposite spin