Theory - Unit 1 - PT & Atomic Structure

Question 1

When is a photon emitted from an atom?

Answer 1

A photon is emitted as an excited electron returns to its ground state.

Question 2

Proton

Answer 2

Positively charged subatomic particle. Contained inside the nucleus. Neutrons and Protons weigh roughly the same (1 atomic mass unit).

Question 3

Nucleus

Answer 3

The center of an atom. Contains the protons and neutrons. Since neutrons have no charge and protons are positively charged, the nucleus has an overall positive charge.

Question 4

Neutrons

Answer 4

Neutrally charged subatomic particle. (No charge) Contained inside the nucleus. Neutrons and Protons weigh roughly the same (1 atomic mass unit)

Question 5

Electrons

Answer 5

Negatively charged subatomic particles. Electrons can be found in the space around the nucleus. This area is often called the electron cloud. Electrons have NO mass.

Question 6

Atomic Number

Answer 6

Identifies an element. The number of protons. For a neutral atom, the number of electrons will equal the number of protons. For an ion (charged atom) the number of electrons will not be the same as the atomic number.

Question 7

Atomic Mass Number

Answer 7

Also known as the Mass Number or Atomic Mass.

Question 8

How to calculate neutrons:

Answer 8

of Neutrons = Atomic Mass Number - Atomic Number

Question 9

Isotopes

Answer 9

Atoms of the same element which have a different Mass Number due to a differing number of neutrons.

The symbol for an Isotope is the element symbol followed by the Mass Number, for example:

Na-23 and Na-24

Question 10

Ions

Answer 10

Atoms or groups of atoms with a charge. To have a charge an atom must have gained or lost electrons. If an atom gains electrons it becomes negatively charged. If an atom loses electrons it will become positively charged.

Question 11

Cations

Answer 11

Positively Charged Ions. In general, cations are metals.

Question 12

Anion

Answer 12

Negatively charged Ions. Anions are negatively charged because they have gained an electron(s) (electrons are negative). In general, anions are nonmetals.

Question 13

Period

Answer 13

Horizontal row on the periodic table.

Question 14

Group or Family

Answer 14

Vertical Column on the periodic table. Elements in the same family have similar properties.

Question 15

Electron Configuration

Answer 15

A shorthand method of writing the location of electrons by sublevels.

Question 16

Photon

Answer 16

Energy given off in the form of light by an excited electron. Otherwise known as a “quanta of light”.

Question 17

Sublevel

Answer 17

Principal energy levels are broken down into sublevels designated s, p, d, or f upon which electrons travel.

Question 18

Orbital

Answer 18

Sublevels can be broken down into regions called “orbitals”. An orbital is defined as the most probable location for finding an electron. Each orbital holds 2 electrons.

Question 19

Orbital Diagram

Answer 19

Shorthand method of writing the location of electrons by orbital.

Question 20

Pauli Exclusion Principle

Answer 20

If there are two electrons in an orbital, they must have opposite (paired) spins.

Question 21

Hund’s Rule

Answer 21

When filling sublevels other than s, electrons are placed in individual orbitals before they are paired up.

Electrons fill like people do on a bus. You would never sit right next to someone you do not know if there are free seats available, unless of course all the seats are taken then you must pair up.

So, when working with the p sublevel, electrons fill like this…up, up, up….down, down, down…

Question 22

Quantum of Energy

Answer 22

Absorbed when an electron moves from its ground state to its excited state.

Question 23

Valence Electrons

Answer 23

Electrons found on the outer energy level. Represented by Roman Numerals. Transition Elements do not have Roman Numerals which denote their valence electrons.

Question 24

Roman Numerals

Answer 24

Above groups/families Roman Numerals represent the number of valence electrons.

When writing the name of an ionic compound which includes a transition metal a Roman Numeral is used to denote the quantity of positive charge associated with that transition metal.

Question 25

Principle Energy Level

Answer 25

The possible locations around an atom where electrons having specific energy values (quantum number) may be found. Divided into sublevels s, p, d, and f.

Question 27

Electronegativity

Answer 27

Tendency of an atom to attract electrons to itself when it combines with another element.

Electronegativity increases from left to right across a period on the periodic table.

Electronegativity decreases as you go down a group on the periodic table.

Question 28

Describe the Bohr Model of an atom.

Answer 28

Question 29

What are the four Quantum Numbers? What do they stand for?

Answer 29

Question 30

Atomic Size

Answer 30

Size of an atom.

Depends on the number of energy levels and the overall charge of the nucleus (the nucleus’s charge depends on the number of protons).

As you go down a group you are adding energy levels (rings around the nucleus) so the atomic size increases.

As you go across a period the atomic size decreases because the energy levels (which contain negative electrons) are increasingly attracted to the positive protons in the nucleus of the atom.

Question 31

How many neutrons does Copper (Cu) have?

Answer 31

59 - 27 =32 neutrons

(Mass # - Atomic # = neutrons)

Question 32

How many neutrons would Pb- 210 have?

Answer 32

210- 82 = 128 neutrons

(mass # - atomic # = neutrons)

Question 33

I have 8 Protons. Who am I? How many electrons do I have?

Answer 33

I identify an element by the number of PROTONS.

Oxygen

8 electrons

Question 34

Draw an isotope of Oxygen.

Answer 34

Your answer should have a different # of neutrons than the Periodic Table.

Question 35

Draw an ion of flourine.

Answer 35

You need to have 1 extra electron than normal.

Question 36

How many pairs of electrons can a p sublevel hold?

Answer 36

3

(The p area is 6 boxes long…6 electrons…3 pairs)

Question 37

What sublevels are in the fifth energy level? The third?

How many total electrons are in the third energy level? The fifth?

Answer 37

Sublevels: Fifth energy level s, p, d, & f. Third energy level s, p, & d.

Total electrons: 18 in the third….32 in the fifth

(count the boxes across that row)