CHEM FINAL

Which ion has the same number of electrons as an argon atom? (A) Mg2+ (B) Cl- (C) Ne (D) Na+

Argon= 18e- (B) Cl- (atomic #17 + -1 charge) =18e-

paramagnetic

Atom or substance containing unpaired electrons

which represents isotopes (in pic)

B (diff neutron # and same element)

PQ-27. Alkaline earth metals form (A) +1 ions. (B) +2 ions. (C) +3 ions. (D) -1 ions.

B) +2 ions

PQ-18. Which group contains nonmetals, metalloids, and metals? (A) 1 (B) 13 (C) 15 (D) 18

C) 15

how many neutrons?? (in pic)

C) 8

PQ-20. The halogens are found in group (A) 1. (B) 15. (C) 17. (D) 18.

C)17

Combustion

CxH2y + excess O2 (g) → nCO2 (g) + yH2O (g) (hydrocarbon)

question on pic

D is the answer

seven diatomic elements

H2, N2, O2, F2, Cl2, Br2, I2

bond order

1/2(bonding-antibonding)

solve

19g(1 mole/52.02g per mole)(2mol F/1 molCH2F2)(6.022x10^23/1moleF) =4.4 x 1023 F atoms

Ti has 22 protons and a 3+ charge and mass of 47amu..what are the electrons, protons and neutrons?

25 neutrons, 22 protons, and 19 electrons. the 3+ only removes electrons

Periodic trend: Electronegativity

Increase Left to Right & Bottom to Top

Net charge

Protons - Electrons; Net charge = zero in a neutral atom

A sample of a gas originally at 25˚C and 1.00 atm of pressure in a 2.5 L container is subject to a pressure of 0.85 atm and a temperature of 15˚C. The final volume of the gas is _____ L. a)3.0 b)2.8 c)2.6 d)2.1 e)0.38

use combined gas law: P1V1/T1=P2V2/T2 P1=1.00 atm P2= .85 atm V1= 2.5 L V2= ?? T= 25ºC= 298.15K T2=15ºC = 288.15K 1 atm x 2.5K/298.15K = .85atm x V2/288.15 V2= 1 atm x 2.5L x 288.15K/298.15K x .85 atm = 2.8L

ANION (nonmetal, polyatomic)

use polyatomic name

look on pic

• Allowed values of n are any integer from 1 to infinity • Allowed values of l depend on the value of the n quantum number. Allowed values of l are 0 up to the value of n- 1. • Allowed values of ml depend on the value of the l quantum number. Allowed values of ml are -l to 0 to + l •Allowed values of ml are either +1/2 or -1/2. The choice with the incorrect set of quantum numbers is choice (B).

periodic trend: reactivity

• Metals: DOWN & LEFT • Nonmetals: UP & RIGHT

Chlorine occurs naturally as a mixture of two isotopes with atomic masses of 34.97 amu and 36.97 amu. What are the relative abundances of these isotopes? (A) 24% and 76% (B) 50% and 50% (C) 76% and 24% (D) 95% and 5%

c) 76% and 24% b/c.. in pic

density

mass/volume

Lithium has two naturally occurring isotopes, 6Li and 7 Li, with masses of 6.015 amu and 7.016 amu, respectively. What is the relative abundance of each isotope? (A) 6Li = 7.49% and 7 Li = 92.51% (B) 6Li = 25.31 %and 7Li = 74.69 % (C) 6 Li = 46.16% and 7Li = 53.84% (D) 6Li = 92.51 % and 7 Li = 7.49 %

(A) 6Li = 7.49% and 7 Li = 92.51% Good video on this type of question: https://youtu.be/6CfSyGd5Ry4 *how to solve a problem like this in pic*

The number of atoms in 9.0 g of aluminum is the same as the number of atoms in (A) 8.1 g of Mg. (B) 9.0 g of Mg. (C) 12.1 ofMg. (D) 18.0 g Mg.

(A) 8.1 g of Mg.

Which pair of particles has the same number of electrons? (A) F-, Mg2+ (B) Ne, Ar (C) Br-, Se D) Al3+, P3-

(A) F-, Mg2+ F on the PT has atomic # 9 but a charge of -1 so this would be F- =10 Mg has an atomic number 12 on the PT and a charge of 2+ so this would bring it to Mg2+=10

Which sample has the largest mass? (A) I mole of marshmallows (C) 1 mole of C02 (carbon dioxide) molecules (B) I mole of Pb (lead) atoms (D) All of these have the same mass.

(A) I mole of marshmallows

A sodium ion differs from a sodium atom in that the sodium ion (A) has fewer electrons. (B) is an isotope of sodium. (C) exists only in solution. (D) has a negative charge on its nucleus.

(A) has fewer electrons.

a pair of isotopes have (A) the same number of protons and a different number of neutrons. (B) the same number of protons and neutrons but a different number of electrons. (C) the same number of protons and the same number of neutrons. (D) the same number of neutrons and the same number of electrons.

(A) the same number of protons and a different number of neutrons.

Which statement is true? (A) The nucleus of an atom contains neutrons and electrons. (B) The atomic number of an element is the number of protons in one atom. (C) The mass number of an atom is the number of protons in the nucleus plus the number of electrons outside. (D) The number of electrons outside the nucleus is the same as the number of neutrons in the nucleus.

(B) The atomic number of an element is the number of protons in one atom.

A 10 gram sample of which substance contains the greatest number of hydrogen atoms? (A) 10 grams ofCH4 (B) 10 grams ofHC1 (C) 10 grams ofH2 (D) 10 grams ofPH3

(C) 10 grams ofH2

What mass of carbon is present in 1.4x 1020 molecules of sucrose (C12H220 11 )? (Molar mass ofC12H22011) = 342 Kmol-1 ) (A) 2.0x 10^22 g (B) 1.7x10^2lg (C) 3.3xl0-2 g (D) 2.8x10-3 g

(C) 3.3xl0-2 g

Which compound below contains a transition metal? (A) NaF (B) AlCl3 (C)VO2 D) BF3

(C)VO2

Which sample contains the least number of atoms? (A) 1.00 g C (B) 1.00 g O2 (C) 1.00 g H2 (D) 1.00 g Fe

(D) 1.00 g Fe

What is the molar mass of K3Fe(C2O4)3? (A) 122.96 g mol-1 (C) 359.10 g-mol-1 (B) 261.15 g-mol- 1 (D) 437.15 g·mol-1

(D) 437.15 g·mol-1

Which statement below is correct? (A) Chlorine is a transition metal. (B) Oxygen is a metal. (C) Sodium is a metalloid. (D) Phosphorous is a nonmetal.

(D) Phosphorous is a nonmetal.

Avogadro's number (Na) (6.022x10^23) equals the number of (A) atoms in one mole of O2. (B) atoms in one mole of atoms. (C) marbles in one mole of marbles. (D) atoms in one mole of atoms and marbles in one mole of marbles.

(D) atoms in one mole of atoms and marbles in one mole of marbles.

question in picture

(E=hv) h= 6.626x10^-34Js v=

alkali metals in compounds are ALWAYS assigned an oxidation state of

+1

hydrogen atoms in compounds are often assigned an oxidation state of

+1

alkaline earth metals in compounds are ALWAYS assigned an oxidation state of

+2

fluorine atoms in compounds are ALWAYS assigned an oxidation state of

-1

oxygen atoms in compounds are often assigned an oxidation state of

-2

R value

0.0821

prefixes (nomenclature)

1-mono 2-di 3-tri 4-tetra 5-penta 6-hexa 7-hepta 8-octa 9-nona 10-deca

Single Replacement

A + BC --> B + AC

triple bond

A chemical bond formed when atoms share three pairs of electrons STRONGEST

double bond

A chemical bond formed when atoms share two pairs of electrons (med strength)

ionic bond

A chemical bond resulting from the attraction between oppositely charged ions. Electrons transferred!! METAL + NONMETAL

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule NONMETAL+NONMETAL

Which element is an alkali metal? (A) K (B) Mg (C) v D)Fe

A) K

combination reactions

A+B--->AB

percent abundance formula

A=m1p1+m2p2 a= average (from periodic table of the element working with) m1= first average mass p1= percent abundance(X) m2= 2nd average mass p2= percent abundance of 2nd mass (1-x)

double replacement

AB+CD ---> AC + BD

Decomposition

AB->A+B

ANION (not polyatomic)

ADD -ide

PQ-29. What is the formula for the compound formed when an aluminum ion, Al3+, combines with an oxide ion, O2 -? (A) AIO B) AL2O3 (C) Al3O2 (D) AIO2

B) AL2O3 (criss-cross method)

PQ-28. Which compound contains a +I ion? (A) MgO (B) KCl (C) NO (D) AlP

B) KCL

PQ-25. Which element is an actinide? (A) Rb (B) U (C) Mo (D) ZnCb (D) Ga

B) U

PQ-19. What is a main group element? (A) Pu (B) Mg (C) Sc (D) Fe

B)Mg

Which compound contains a Group 14 metal? (A) CCl4 (B) SnCb C) GeF4 D) ZnCl2

B)SnCb

which displays the correct answer (in pic)

C

Two isotopes of hypothetical element X exist with abundances of 30.00% 100X and 70.00% 101X. what is the approximate atomic mass of X (in atomic units, amu)? (A) 100.3 (B) 100.5 (C) 100.7 (D) 101.0

C) 100.7 avg atomic mass= M1X1+M2X2 = 100x0.3 + 101x0.7 = 30+70.7 =100.7

PQ-26. Magnesium forms an ionic compound with an element with the formula MgX. Which ion could be X? (A) Br- (B) p3- (C) C4- (D) S2-

D) S2- Mg has a 2+ charge so this will need a 2- to balance it (nonmetal)

Which atom has the most neutrons? (A) neon-20 (C) chlorine-35 (B) phosphorous-32 (D) sulfur-35

D) sulfur-35 (less protons than Cl-35)

PQ-30. If gallium, atomic number 3, combines with selenium, atomic 34, what is the most likely formula based on your knowledge of the periodic nature of the elements? (A) GaSe (B) GaSe2 (C) Ga2Se D)Ga2Se3

D)Ga2Se3 USE CHARGES

In all neutral atoms, there are equal numbers of (A) protons and neutrons. (C) neutrons and electrons. (B) positrons and electrons. (D) electrons and protons.

D)electrons and protons

formula used in last question??

FIRST USE RYDBERG THENN DO WAVELENGTH CALCULATION (wavelength=hc/ephoton) THEN DO IT IN NM

naming rule for 1st and 2nd word

FIRST WORD- most metallic (or farthest to the left on PT) IF IN THE SAME GROUP THEN GO ONE DOWN FOR 1ST WORD SECOND WORD- least metallic ex. PCl5, SF6, CO2

solve

Fe3= 55.85 x 3 = 167.55 O4= 16 x 4 = 64 sum Fe3O4 = 231.55 Fe3 contribution= (167.55/231.55)x 100 = 72%

formal charge

Formal charge = (number of valence electrons in a free atom of the element) - (number of unshared electrons on the atom) - (number of bonds to the atom)

How many protons (p+), neutrons (n°), and electrons (e-) are present in (on image)

From the symbol, you see that the atomic number is 22, which means that it has 22 protons. The mass number is 47, which means 47 - 22 = 25 neutrons. You see that the charge of the ion is a positive three (3+ ). This means that the atom has three more protons than electrons. This happens when electrons are removed from the atom, forming the ion. Therefore, the number of electrons is 22 - 3 = 19. The correct choice is (A).

periodic trend: size

INCREASING: down DECREASING: to the right larger atomic number(protons)=larger atomic radius

Periodic trend: Ionization Energy

Increase Left to Right & Bottom to Top

molarity (M): the concentration of a solution expressed in moles of solute per liter of solution

M= moles solute / liter solution

atomic mass

Number of protons and neutrons (protons + neutrons)

ideal gas law

PV = nRT

What is the formal charge of each atom (from left to right) in the following Lewis structure of SN2? a) 0, 0, 0 b) -1, +1, 0 c) -2, +1, 0 d) -2, -1-, +1 e) -1, -1, +1

S: 6-6-1= -1 N: 5-0-4= -1 N: +1 e) -1, -1, +1

group 1 and (NH4+)

SOLUBLE

In the energy diagram, transitions between energy levels are denoted by arrows. Which transition corresponds to the absorption of the shortest wavelength of light? (A) E2 to E1 (C) E3 to E2 (B) E2 to E3 (D) E1 to E3

So, the longer the arrow the more energetic the photon. Remember that photon energy and wavelength are inversely related. The question is asking you to find the transition with the shortest wavelength, which means the highest energy (longest arrow). The question also wants the transition to be an absorption (upward pointing arrow). The correct choice is (D).

In which atom does a 2p electron experience the greatest effective nuclear charge, Zeff (A) B (B) C (C) F (D) N

The correct choice is (C).

If the formula of an ionic oxide of element X is X2O3, what is the formula of the chloride of X? (A) XCl3 (B) XCI (C) X3Cl (D) XC16

To make a neutral species when you combine X3 + and cl-, you need three cl- for each X3+. The correct formula would be XCl3. This is choice (A).

sig figs ADDITION

USE DECIMAL PLACE

The pressure of a sample of CH4 gas (6.022 g) in a 30.0 L vessel at 402 K is ______ atm. a)2.42 b)6.62 c)0.413 d)12.4 e)22.4

USE: P=nRT/V c)0.413

The element thallium, Tl, has two stable isotopes, 203Tl and 205Tl. Which statement correctly describes the relationship between the relative abundances of these two isotopes? (A) %abundance of 203Tl >%abundance of 205Tl (B) %abundance of 203Tl =%abundance of 205Tl Not enough information is provided to (C) %abundance of 203Tl <%abundance of 205Tl (D) determine the relationship .

You compare the average atomic mass, 204.4 amu, to the masses of the two isotopes. The average atomic mass is closer to the 205 amu than it is to 203 amu. This means that the% abundance of 203Tl isotope is less than the% abundance of 205Tl isotope. The correct choice is (C)) %abundance of 203Tl <%abundance of 205Tl good vid on this: https://youtu.be/ZtKuHxJXH6I

Which group number contains the most diatomic molecular elements? (A) Group 1 (B) Group 16 (C) Group 17 (D) Group 18

You recall that the seven diatomic molecular elements are: H2, N2, O2, F2, Cl2, Br2, and I2. When you refer to the periodic table at the beginning of the study guide (p. 11) you see that four of these elements occur in Group 17. The correct choice is (C).

What is the classification of sulfur? (A) metal (B) metalloid (C) semiconductor (D) nonmetal

You remember that the element symbol for sulfur is S. This element is located in the third period and Group 16. Sulfur lies above and to the right of the line that separates metals and nonmetals. Elements in this region of the periodic table are classified as nonmetals. The correct choice is (D).

Which type of electron is described by the quantum numbers, n = 3, l = 2, ml = 1, and ms = + 1/2? (A) 2p (B) 3p (C) 3d (D) 3f

You return to the given set of quantum numbers and decide the type of electron being described: n = 3 and l = 2 describes a 3d electron. The relationship between the letters and the values of the l quantum number are: l = 0 is an s orbital; l = 1 is a p orbital, l = 2 is a d orbital, and l = 3 is a f orbitaL The correct choice is (C).

polar covalent bond:

a bond characterized by unequal sharing of bonding pairs of electrons between atoms

nonpolar covalent bond:

a bond in which the electrons are shared equally

empirical formula

a formula with the lowest whole-number ratio of elements in a compound

Solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide. In a particular experiment, the reaction of 2.5 g of Al with 2.5 g of O2 produced 3.5 g of Al2O3. The % yield of the reaction is_____. 4 Al (s) + 3 O2 (g) → 2 Al2O3 (s) a)74% b)37% c)47% d)66% e)29%

a)74%

Accuracy vs. Precision

accuracy: how close experimental value is to accepted value; precision: how closely measured values agree with each other

% yield

actual yield/theoretical yield x 100 percent yield is where its A/T!

Stoichiometry: changing coefficient changes..

amount of atoms

What is an ion?

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

An atom of strontium-90, ~~ Sr, contains (A) 38 electrons, 38 protons, 52 neutrons. (C) 52 electrons, 52 protons, 38 neutrons. (B) 38 electrons, 38 protons, 90 neutrons. (D) 52 electrons, 38 protons, 38 neutrons

answer is A because the amu mass is 90 but to get neutrons you subtract 90-38=52 neutrons. 38 is both the number of electrons and protons

neutrons

atomic mass-proton number

average mass

avg= ∑aimi ai= natural abundance of isotope i mi= mass of isotope i

Which of the following bonds is most polar? a) B-H b) N-H c) P-H d) Al-H e) C-H

b) N-H

solve

c) 119 FIRST FIGURE OUT HOW MUCH OF EACH REACTANT + FIND LIMITING REACTANT: moles of NH3 = 43.9 / 17 = 2.582 moles of O2 = (258 / 32) = 8.063 here, NH3 is the limiting reactant So, molmolees of NO2 formed = 2.582 mass of NO2 = 2.582 x 46 = 119 g Therefore, the answer is 119 g

Which term best describes the relation of hydrogen (1H) to deuterium (2H)? (A) allotropes (B) isomers (C) isotopes (D) polymers

c) isotopes

stoic: changing subscripts..

changes identity and properties

Which isoelectric series is correctly arranged in order of increasing radius? a) K+ < Ca2+ < Ar < Cl- b) Cl- < Ar < K+ < Ca2+ c) Ca2+ < Ar < K+ < Cl- d) Ca2+ < K+ < Ar < Cl- e) Ca2+ < K+ < Cl-

d) Ca2+ < K+ < Ar < Cl-

Which of the following Lewis structures would be an expansion to the octet rule? a) SiF4 b) CF4 c) CCl4 d) PO43- e) NF3

d) PO43-

solve

d) is the answer bc it is incorrect N2 is not nitrite it would be nitride nitrite (NO2)2

isotopes

differ in number of neutrons BUT same number of protons

METAL (ionic CATION with multiple charges NOT possible)

elemental name

the sum of the oxidation states of all atoms in any given species is ____________ on that species.

equal to the net charge

The molarity of an aqueous solution containing 75.3 g of glucose (C6H12O6) in 35.5 mL of solution is ______. a)14.8 b)2.12 c)481 d)0.0118 e)11.8

glucose: 75.3g MW= 180 V= 35.5 mL M= (W/ MW) x (1000/V) = 75.3 / 180 x 1000/35.5 = 75300/6390 = 11.8 M OR SOLVE LIKE PIC

n numbers get closer together as they

go up

SIG FIGS

good description in pic

Ag+, Pb2+, Hg+ salts

insoluble

sig figs in multiplication and division

least number of sig figs

nonbonding pair

lone pairs (dots)

solve

moles O2= (4.32x10^21 mol / 6.022 x 10^23 moles) = .717^-2 = .00717 mole NOW DO RATIO OF 3 mole g 02 TO 4 FeCl2 moles of FeCl2 needed= 4/3(0.00717) = .00956 mol FeCl2 vol of FeCl2= 0.00956 mole/ .945 mole/L =0.010L = 10.1 mL

are assigned an oxidation state of their own charge

monoatomic ions

emission

n number goes from high to low (falling)

excitation

n number going low to high

steric number

number of atoms bonded to central atom + number of lone pairs on central atom (count lines and lone pairs)

Avogadro's number

number of representative particles (things) in a mole, 6.022 X 10^23

Avogadro's number

number of representative particles in a mole, 6.02 X 10^23

prefixes

on pic

Single bonds:

one sigma bond

Double bonds:

one sigma bond, one pi bond

Triple bond:

one sigma bond, two perpendicular pi bonds.

who can have an expanded valance shell

rows 3 and below

molecular formula

the # of each type of atom in a molecule MULTIPLE OF THE EMPIRICAL FORMULA

mass percent

the % by mass an element contributes to a compound calculated by: mass% of X in compound Y= (mass of X/ mass of compound Y)x100

lighter gas

the faster the effusion rate

reduction

the gain of electrons (when the oxidation state is lowered or reduced)

oxidation:

the loss of electrons— results in a higher oxidation state

Atomic number (Z number)

the number of protons and electrons in an atom DEFINES ELEMENT

electron domain

the region where electrons are most likely to be found

heavier gas

the slower the effusion rate

Shorter bond length

the stronger the bond

periodic trend: Zeff

up and to the right

NONMETAL (covalent) what happens for the name?

use prefixes N2O5---> dinitrogen pentoxide

METAL (ionic CATION with multiple charges possible)

use roman numerals Fe2O3 ---> iron(II)oxide

longer bond length

weaker bond

single bond

weakest

1. an individual element uncombined with other elements has an oxidation state of

zero

What is the wavelength of light (in nm) produced by the electronic transition between levels 4 and 2 of a hydrogen atom? (A) 182 nm (B) 364 nm (C) 486 nm (D) 1450 nm

∆E=Rh(1/ni^2-1/nf^2) Rh= 2.18x10^-18 J Ni=4^2 Nf=2^2 plug in: 2.18x10^-18(1/16-1/4)= 4.09x10^-19J now use: Ephoton= hc/wavelength h = 6.626x10^-34Js c= 2.998 x 10^-8 ms^-1 ephoton= 4.09x10^-19 J WE WANT WAVELENGTH SO USE: lambda = hc/ephoton lambda= (6.626x10^-34Js)(2.998 x 10^-8 ms^-1) / 4.09x10^-19 J = 4.86 x 10^-7m x 10^9 nm/1m =486nm

energy of a photon

e=planck's constant*frequency (E=hv)