AP Chem: Lesson #1 Quiz

How much do protons, neutrons, and electrons weigh

1, 1, ~5 × 10^-4 amu

Which element has 56 protons and how many neutrons does it have

Barium has 81 neutrons

Isotopes

Versions of a same element that are heavier/lighter and have a difference in atomic weight (e. Neon-21 —> +1 neutron)

Relative abundance

How frequently something occurs or what percent of something there is

Average atomic mass =

Mass of isotope x relative abundance (decimal)

Mass spectometry

Analyzing the mass of an element (graph)

Mole value

6.022 × 10^(23) particles/molecules/atoms of a substance in a mole

If I have 2 moles of H2O how many grams of H2O do I have?

36g H2O

H2O molar ratio

2:1 Hydrogen/Oxygen

C6H12O6 molar ratio

1:2:1 Carbon/Hydrogen Oxygen

Percent by mass

The ratio of the mass of a component to the total mass of the mixture, expressed as a percentage. It is calculated by dividing the mass of the component by the total mass and multiplying by 100.

Percent by mass of oxygen in H2O

16/18.016 = 0.88 = 88%

Empirical formula

Make an assumption that the sample weighs 100g

A compound is composed of 40% Carbon, 6.7% Hydrogen,a ND 53.3% Oxygen. Find it’s Empirical Formula

C1H2O1

If C1H2O1 weighs 60g per mole, what is the Molecular Formula?

C2H4O2

RA x ___ of an object should equal the weighted average of an isotope on the periodic table.

mass

Electrons on the outer orbital have more _____.

energy

More electrons, more _______.

negativity

Anion

Negative elements —> new ones end in -ide

Shells

2, 8, 18, 32

T/F: Valence electrons are based upon groups including transition metals.

False, not including transition

How many electrons in each orbital

2

1st shell subshell

s

4th shell subshells

spdf

Noble gas configuration

A shorthand notation to represent the electron configuration of an atom using the electron configuration of the nearest noble gas preceding the element, followed by the electron configuration of the valence shell. ONLY WHEN ITS JUST THE NOBLE GAS IN BRACKETS

Exceptions to orbitals elements (main)

Cu (Copper) and Cr (Cromium)

Cu orbital exception

4s does not fill before 3d (takes one from 4s² to finish the 3rd shell) and only has a +1 charge because of 1 valence electron

Cr orbital exception

Should be 3d^4, but takes 1 from 4s to be 3d^5 (because 4s² electrons don’t go well together, it’s better since 3d^5 electrons aren’t paired)

T/F: Electrons don’t like being in pairs unless they need to.

True

T/F: Shielding electrons are all electrons but valence.

True

T/F: Outer electrons are everything but valence.

False. They ARE valence

Coulomb’s Law

F(level of attraction) oc (q1q2)/r2

• oc = approximated

• q1 = charge of electron

• q2 = effective nuclear charge of protons

T/F: If two charged particles are closer and the element is bigger, there’s more attraction.

True

F(level of attraction)

Ionization energy (needed to take away electrons) —> high amount if holding onto closely

Shielding

When inner electrons prevent outer electrons from getting close to the nucleus

T/F: Effective nuclear charge is = to valence electrons.

True

T/F: Effective nuclear charge = protons - shielding electrons.

True (e. 11p - 10 = +1 charge)

Photo electron spectroscopy

A technique used to measure the energy of electrons emitted from atoms or molecules when they absorb photons, providing information about the electronic structure and binding energies.

Graphs of Photo electron spectroscopy

• y-axis = # of electrons

• x-axis = binding energy (how strong electrons were holding on)

T/F: You can’t remove outer electrons while having inner electrons.

False. You can’t remove inner electrons while having outer.

Electrons with the least amount of energy =

Less close to nucleus

Electrons closer to the nucleus =

More attracted (element bound tight)

What does oxygen’s Photoelectron Spectroscopy graph being more left than aluminum’s mean?

It’s holding onto its electrons more tightly

Level of attraction =

(pos. charge & neg. charge)/distance of them

Ionization energy

Energy required to remove an electron from an atom; how tightly the electrons are held to the atom

T/F: Down and left ionization energy increases.

False. Up and right it increases.

T/F: There’s higher ionization energy because there’s higher effective nuclear charge.

True

T/F: 10,000 kJ is a high energy needed to remove electrons.

True

Nucleus charge

Positive

IE1 (Ionization Energy 1) might be lower than another element because why?

That other element might have more protons

Atomic Radii

The distance between the nucleus and the outermost valence electron

What two things affect atomic raddii?

The effective nuclear charge and the amount of electron shells

T/F: The higher the effective nuclear charge means the more tightly an atom holds onto its electrons

True

Ionic Radii become larger because why

Adding an electron with the same effective nuclear charge means the new electron won’t be held closelyby the nucleus due to increased electron-electron repulsion.

T/F: Losing an electron makes the Atomic Radius smaller because there’s less repulsion.

True

Electronegativity

The tendency for an atom to attract electrons toward itself

What two things affect electronegativity?

Effective nuclear charge and the amount of electron shells

Element with the highest electronegativity

Flourine (smallest atom of ENC with the octet)

T/F: The larger an atom gets and the weaker its nuclear charge the less likely it will hold electrons closely.

True

Rank from the smallest-largest radii: He, Na, F, O, Fr

He, O, F, Na, Fr

Rank from the smallest-largest ionization energy: Fe, Cl, K, F, O

K, Fe, Cl, O, F

Rank from the smallest-largest electronegativity: Br, Rb, Mg, Ga, Cl

Rb, Mg, Ga, Br, Cl

Atomic vs. ionic radii

Atomic radii refer to the size of neutral atoms, while ionic radii refer to the size of ions, with cations generally being smaller and anions larger than their parent atoms.

Trend for ionization energy from left to right

Higher to the right

Trend for Atomic Radius going top to bottom

Higher (more) at the bottom

Trend for Atomic Radius from left to right

Higher on the left

Why is the Ionic Radius of Be smaller than the atomic radius of Li?

Be’s 2 valence electrons that it loses leave and leave Be with the 2 electrons left on its first level which leaves these electrons to be more tight to the nucleus and have a greater effective nuclear charge making the molecule tighter and smaller; neutral Li doesn’t lose any electrons and has that electron in the second energy level, far from the nucleus (stretches out the element)

Carbon-13 number of protons, neutrons, electrons

6, 7, 6

Carbon-13 abundance

1.07%

Carbon-13 atomic mass

13.003

Is Carbon-13 stable or unstable?

Stable

• X-10 has a mass of 10.00 amu

• X-11 has a mass of 11.00 amu

• The average atomic mass of X is 10.80 amu

• What is the relative abundance (%) of X-10 and X-11?

X-10 is approximately 40% and X-11 is approximately 60%.

• Y-20 has a mass of 20.00 amu and an abundance of 75%

• Y-? has an abundance of 25%

• The average atomic mass is 20.50 amu

• What is the mass of Y-?

21.00 amu

Element Z has two isotopes:

• Z-30: 30.00 amu, 40% abundance

• Z-32: 32.00 amu, 60% abundance

• What is the average atomic mass of Z?

31.20 amu

Newtons

Measurement in physics of how much force of attraction/repulsion there is between two objects

T/F: Electrons farther away from the nucleus when q2 and q1 are positive have less attraction as they are farther away from the nucleus.

True

T/F: Newtons of force decrease as electrons move away from protons and as electrons move shells.

True

Shielding

When inner-core electrons repel outer-valence electrons

Why is the outermost electron of lithium most likely to be lost and why is it hard to remove the interior 2 electrons?

The outermost electron of lithium is most likely to be lost because it is further from the nucleus and experiences less attraction due to shielding effects from the inner electrons. The interior 2 electrons are harder to remove because they are closer to the nucleus and experience a stronger electrostatic attraction.