test 1- theory, config., periodic trends, forces

Question 1

Whatre the three bohr postulates

Answer 1

1. Atoms have energy levels (shells) for electrons
2. When moving within the same shell, electrons do not radiate energy
3. When moving between shells, eletrons absorb or emit energy

Question 2

What is the ground state of an electron, why is it preferred

Answer 2

The lowest energy state of an electron, when it is as close to the nucleus as possible
Doesnt require energy to stay at the energy state, can stay there

Question 3

What do electrons act like, what do they give off

Answer 3

They can act as waves, not just particles
They give off small energy particles called quanta when moving from higher to lower energy states

Question 4

Whats the difference between an electron acting as a particle and acting as a wave

Answer 4

When as a particle: it has a definite position and mass, when acting as a wave: it is spread out over a region of space, so the position is uncertain (thats why the orbital is a space where an electron MIGHT be)

Question 5

Whatre energy levels split into

Answer 5

Subshells and orbitals

Question 6

Whats a subshell and orbital, what types of subshells are there, how many orbitals are found in each subshell

Answer 6

A subshell is a group of orbitals (s, p, d, f)
An orbital is the region of space occupied by an electron
S subshells hold 1 orbital
P subshells hold 3 orbitals
D subshells hold 5 orbitals
F subshells hold 7 orbitals

Question 7

Howre orbitals shaped, how many electrons can each of them hold

Answer 7

The shape of the orbitals depend on which subshell it comes from, each can hold two electrons

Question 8

What do quantum numbers describe, whatre the four types

Answer 8

They describe the orbitals and electrons found in a certain element
Principle quantum (n): which energy level (shell) the electron is found on
Angular momentum (l): which subshell the electron is found on (0=s, 1=p, 2=d, 3=f), l is smaller or equal to the principle number minus one
Magnetic quantum (ml): the orientation of the orbital/ which orbital in the subshell the electron is found on, ml=-l…l
Spin quantum (ms): the spin of the electron/ which of two electrons is on the orbital, can be +1/2 or -1/2

Question 9

Whats the pauli exclusion principle

Answer 9

No two electrons in the same atom can be described by the same set of quantum numbers

Question 10

What does an electron configuration describe

Answer 10

How all the electrons are arranged in atomic orbitals for a specific element

Question 11

Whats the aufban principle

Answer 11

When filling orbitals, the lowest energy orbitals available are filled first

Question 12

Whats the hunds rule

Answer 12

When orbitals of equal energy are being filled, electrons are most stable when each electron is single occupied before being paired

Question 13

What is special about elements with d4 or d9 subshells

Answer 13

A filled or exactly half filled d-subshell is especially stable, so an elecctron from the s subshell may move to the unfilled d-subshell

Question 14

What is atomic radius, how does it increase and decrease on a periodic table, how does the radius change for cations and anions

Answer 14

How far the valence electrons are from the central nucleus
Increases moving down a group, decreases moving left to right across periods
Cations: decreases (grows smaller), anions: increases (grows larger)

Question 15

What is the shielding effect

Answer 15

Electrons from the inner shells of an atom repel the valence electrons

Question 16

What is electronegativity and its relationship to atomic radius, how does it increase/decrease on a periodic table

Answer 16

Is the inverse of atomic radius
Is the ability of an atom to draw bonding electrons to itself
Decreases moving down a group, increases moving left to right (more protons=stronger pull on electrons)

Question 17

How does the shielding effect affect atomic radius and electronegativity/ionization energy

Answer 17

The shielding effect repels the valence electrons further (makes atom larger), it weakens the attractive force between the valence electrons and the nucleus (decreases ionization energy/ makes electronegativity weaker)

Question 18

How do the periodic trends affect halogens and alkali metals

Answer 18

Alkali metals: largest element in period/ low ionization energy/ less electronegativity (most left= most repulsion)
Halogens: highest electronegativity/ highest ionization energy, smallest element in period (most right= most attraction)

Question 19

Whatre the three exceptions in the lewis structures

Answer 19

1. Elements in group 1, 2, and 13 tend to form compounds when surrounded by fewer than eight electrons (ex. BF3 or BCl3, pay attention to boron)
2. Atoms in period 3 or higher can form compounds with more than four other atoms/ use more than eight electrons due to the access of the d orbital (ex. SF6)
3. Some compounds can have an odd total number of valence electrons (those molecules are called radicals and are very unstable) (ex. NO2 with 17 electrons in total)

Question 20

Whatre intramolecular forces and some examples

Answer 20

The bonds within molecules
Ex. Covalent, ionic

Question 21

How can a bond be formed between atoms, what state is the molecule in after being bonded

Answer 21

When the attractive forces are stronger than the repulsion (the negative electron clouds exert repulsive forces that slow approaching atoms)
In a lower energy state than when they were apart due to their newfound stability

Question 22

What shapes do ionic compounds form

Answer 22

Crystal lattices

Question 23

Whats a dipole, whats the difference between a bond dipole and the dipole moment

Answer 23

The separation of electrical charges within a molecule (has a more positive and a more negative end)
Bond dipoles form between each central atom and bonded atom, showing the charges of those parts only
The overall dipole moment indicates the overall charge of the molecule, accounting for symmetry

Question 24

Whatre lone pairs, how do the ones on the central atom affect the shape/structure/ symmetry/ polarity of the molecule

Answer 24

Lone pairs are the electrons found on the atom thatre not bonded with another atom, they repel the bonded atoms, bending the molecule and making it asymmetrical and therefore polar

Question 25

What does VSEPR stand for and what does it describe

Answer 25

Valence shell electron pair repulsion
Describes the molecular shape of a molecule, accounting for repulsion

Question 26

Whatre the three components of axe notation and what does it describe

Answer 26

A= central atom
X=bonding/branching atoms (substituient group)
E=lone pairs on central atom
A writing system used to describe the geometry of molecules based on repulsion (not the actual model, just the writing form)

Question 27

Whatre the six axe notations, what angles, polarity, and shapes are they

Answer 27

Ax2: linear, nonpolar, 180
Ax3: trigonal planer, nonpolar, 120 (ex. Bf3)
Ax2e: bent, polar, 120
Ax4: tetrahedral, nonpolar,109.5
Ax2e2: bent, polar, about 109.5
Ax3e: trigonal pyramidal, polar, 109.5

Question 28

Whatre intermolecular forces, whats another name for them

Answer 28

The forces between molecules
Van der waals

Question 29

Which is weaker: intramolecular, intermolecular

Answer 29

Intermolecular, but they can still be very strong in large numbers

Question 30

Whatre london forces, howre they formed, what molecules are they found in

Answer 30

Weak, attractive forces that induces a temporary dipole on a nearby atom (by chance, moving electrons within an atom mostly move to one side, causing the atom itself to be polar and causes nearby atoms to also become polar and be attracted)
Found in all molecules, but are most prominent in nonpolar ones because theyre only significant when no stronger forces are present

Question 31

Whatre dipole dipole forces

Answer 31

Attraction between polar molecules with permanent dipoles

Question 32

Whatre hydrogen bonds, what atoms can they be formed by

Answer 32

Formed between hydrogen and nitrogen/oxygen/fluorine atoms
The strongest type of dipole dipole attractions

Question 33

Whyre hydrogen bonds the strongest out of all the intermolecular forces

Answer 33

Nitrogen, oxygen, and fluorine are highly electronegative due to their nuclear charge and small size, pulling the hydrogen’s electrons so strongly that a very strong dipole is created

Question 34

Howre melting and boiling points of molecules affected by the intermolecular forces

Answer 34

The stronger the intermolecular forces (ex. Dipole dipole, hydrogen bonding), the higher the melting and boiling points due to the amount of energy required to break the bonds