CHEM 103 Lecture Notes - Lecture 6: Magnesium Carbonate, Chemical Formula, Electric Light

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2 Nov 2017

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A negative potential indicates attraction between ions. As the magnitude of the potential increases, the bond gets stronger. Compare the melting points of nacl, al2o3, and csbr. Which one is the correct order: nacl < csbr < al2o3, al2o3 < csbr < nacl, csbr < nacl < al2o3, all the same as they are all ionic compounds. Correct answer: c (look athe the charges of the compounds; al2o3 has the largest charge=largest melting point) A polyatomic ion is a unit of two or more atoms that bear a net electrical charge. What is the molecular formula for magnesium carbonate, which is used by athletes for chalk: mgco3, mg2co3, mg(co3)2, mg3(co3)2. What is the molecular formula for sodium phosphate which is found in pedia- What is the chemical formula for iron sulfate: feso4, fe2so4, fe2(so4)3, need more information. Correct answer: d-iron has two diferent charges the element can take on.

Related Questions

1. Which of the following pairings regarding protein structure is/are incorrect?

Question options: a) primary structure: alpha helix

b) quaternary structure: hydrophobic interactions between different regions of the same polypeptide strand

c) tertiary structure: interactions between R groups on different polypeptide chains

d) secondary structure: hydrogen bonding between R groups on the same polypeptide strand

e) All of the above are incorrect.

2. Given the following pairs of amino acids, which pair contains the correct type of interaction through which the two amino acids most likely interact?

Question options: a) valine and leucine: charge-charge (salt bridge)

b) threonine and cysteine: disulfide bond

c) aspartic acid and glutamic acid: hydrophobic interaction

d) threonine and serine: hydrogen bonding

e) None of the above is correct.

3. Which statement is correct regarding the comparison of the following three tripeptides:

1) lys-lys-lys

2) asp-asp-asp

3) lys-asp-val

Question options:

a) Under physiological conditions, peptide #1 elutes last using cation exchange chromatography.

b) Under physiological conditions, peptide #2 elutes first using anion exchange chromatography.

c) Under physiological conditions, peptide #3 elutes last using anion exchange chromatography.

d) Under physiological conditions, peptide #3 elutes first using either cation or anion exchange chromatography.

4. When varying the substrate concentration at a fixed concentration of enzyme it is observed that at low concentrations of substrate the reaction is ________ (with respect to substrate),while at high concentrations of substrate the reaction is ________ (with respect to substrate).

Question options: a) initial; maximal

b) maximal; initial

c) second order; first order

d) first order; zero order

4. (20 pts, 2 pts each) Multiple choice questions from chapter 7.Place the letter representing the
correct response in the blank provided.
_____ Which of the following do not exist under normal conditionsas a diatomic gas?
(A) hydrogen, (B) oxygen, (C) fluorine, (D) chlorine, (E)bromine
_____ In nature, the noble gases exist as
(A) monatomic gaseous atoms, (B) the gaseous fluorides, (C) solidsin minerals,
(D) alkali metal salts, (E) the sulfides
_____ Of the elements below, _____ has the highest electronaffinity.
(A) oxygen, (B) sodium, (C) fluorine, (D) hydrogen, (E)chlorine
_____ Of the following elements, which has the largest firstionization energy?
(A) Se, (B) As, (C) S, (D) Sb, (E) Ge
_____ Of the hydrogen halides, only _____ is a weak acid.
(A) HCl (aq), (B) HBr (aq), (C) HF (aq), (D) HI (aq), (E) all ofthem
_____ The carbonate of which alkali metal is used in treatment ofmanic-depressive illness?
(A) Li, (B) Na, (C) K, (D) Rb, (E) Cs
_____ The reaction of a metal with a nonmetal produces a(n)
(A) base, (B) salt, (C) acid, (D) oxide, (E) hydroxide
_____ Which element is solid at room temperature?
(A) Cl2, (B) F2, (C) Br2, (D) I2, (E) H2
_____ Which of the following correctly lists the five atoms inorder of increasing size (smallest to
largest)?_(A) F < K < Ge < Br < Rb, (B) F < Ge <Br < K < Rb,
(C) F < K < Br < Ge < Rb, (D) F < Br < Ge < K< Rb, (E) F < Br < Ge < Rb < K
_____ Which one of the following is a metalloid?
(A) Ge, (B) S, (C) Br, (D) Pb, (E) C
5. (20 pts, 2 pts each) Multiple choice questions from chapter 8.Place the letter representing the
correct response in the blank provided.
_____ Which of the following ions does not have a noble-gasconfiguration?
(A) V5+ (B) Si4+ (C) Nb3+ (D) S2â (E) Os8+
_____ Which of the following is correctly arranged with respect tothe size of the atom/ion?
(A) S < S1â < S2â (B) Mg2+ < Na+ < Ne (C) Ni < Cu+< Zn2+
_____ What type of covalent bond between like atoms is thelongest?
(A) triple (B) double (C) single (D) They are all the samelength.
_____ Arrange the following in order of increasing bond polarity:C-O, P-O, Cu-O, Mn-O
(A) C-O < P-O < Cu-O < Mn-O (B) C-O < P-O < Mn-O< Cu-O
(C) Mn-O < Cu-O < P-O < C-O (D) P-O < C-O < Cu-O< Mn-O
_____ Write a single Lewis structure that obeys the octet rule, andcalculate the formal charges on
all the atoms in PO4
3â.
(A) P 2+, O 1â (B) P 1+, O 1â (C) P 4+, O 2â (D) P 2+, O 2â (E) P1+, O 2â
_____ The Lewis structure of InBr3 contains how many valenceelectrons?
(A) 24 (B) 7 (C) 6 (D) 3 (E) 34
_____ Using Lewis structures that satisfy the octet rule, determinethe number of bonds formed by
the central element in each of the following: SiO4
4â, PO4
3â, SO4
2â, ClO4
1â.
(A) 4, 5, 6, 7 (B) 2, 3.5, 5, 6.5 (C) 4, 5, 5, 6 (D) 4, 4, 4, 4 (E)5, 6, 7, 8
_____ The Lewis electron-dot structure of IF5 gives the centralI
(A) an octet (B) 5 nonbonding pairs and 1 bonding pair (C) 5bonding pairs only
(D) 1 nonbonding pairs and 5 bonding pairs (E) 1 nonbonding pairand 4 bonding pairs
_____ In the thiocyanate anion, (SCN)â, which of the following isnot an accepted multiplicity for
the sulfur-carbon bond and the carbon-nitrogen bond,respectively?
(A) single, single (B) double, double (C) single, triple (D)triple, single
_____ Which of these ions (oxidation states) does not have anoble-gas configuration?
(A) Cr3+ (B) Cr with an oxidation state of 6+ (as in CrO4
2â)
(C) S with an oxidation state of 6+ (as in SO4
2â) (D) S2â (E) Hf 4+

1)The NaCl2 ionic salt does not exist. Which of the followingstatements best explains why?

A. Because the formation of Na2+ is an unfavorable process due tothe great amount of energy required to remove the 2nd electron fromthe Na atom (the 2nd electron would have to be removed from thecore electrons of the Na atom).
B. Because the Cl- anion is too large for there to be two of themattached to one Na+ ion.
C. Because NaCl2 is actually a polyatomic ion with a -1 charge, andnot an ionic salt. In the presence of another Na+ ion, the Na2Cl2salt would form.
D. Because Cl2 has no charge and therefore would not be attractedelectrostatically to the positively charged Na2+ cation.

2)Select the false statement below.

A. The first ionization energy of an atom is smaller than thesecond ionization energy of the same atom.
B. Phosphorus has a greater first ionization energy than magnesium,and the reason for this is because P has a greater effectivenuclear charge (Zeff) than Mg.
C. The following process is an endothermic process and representsthe first ionization energy of an atom A:A(g) ? A1+(g) + e1-
D. Fluorine has a greater first ionization energy than iodine, andthe reason for this is because fluorine has a greater amount ofshielding of outer electrons by inner electrons than doesiodine.

3)The Group 5A elements N,P,As have lower (less negative) electronaffinities than most of the Group 4A or Group 6A elements becauseN,P,As have half-filled subshells.

True
False

4)A fluorine atom is smaller than a bromine atom, and a potassiumatom is larger than a lithium atom.

True
False

5)A certain main-group element exhibits the following successiveionization energies in kJ/mol:

IE1 = 100; IE2 = 1200; IE3 = 2300; IE4 = 3100; IE5 = 4200

Select the false statement about this element below.

A. This is likely a Group 1A element.
B. This element is typically found uncombined in nature (that is,it is not usually found in compounds, but rather as a freeelement).
C. If this element is given a symbol of "J", it would form an ioniccompound with sulfur as J2S.
D. If this element was in period 2 of the periodic table, it wouldbe lithium.

6)Select the false statement below.

A. Generally speaking, non-metallic elements have greater effectivenuclear charge (Zeff) than metallic elements in the sameperiod.
B. Generally speaking, as you go down a group in the periodictable, there is successively greater shielding of the outer-shellelectrons by the inner-shell electrons.
C. Generally speaking, the heavier alkali metals can be predictedto exhibit greater shielding of the outer-shell electrons by theinner-shell electrons than lighter alkali metals.
D. Generally speaking, as you go across a period in the periodictable, the effective nuclear charge (Zeff) decreases because eachsuccessive element contains more protons in the nucleus than theprevious element and the outer electrons are all in the same shellas you go across a period.

7)Place the following in order of increasing size:

O2-, F1-, Li1+

A. F1- < Li1+ < O2-
B. Li1+ < O2- < F1-
C. Li1+ < F1- < O2-
D. F1- < O2- < Li1+

8)Select the false statement below.

A. The following set of quantum numbers is allowed:
n = 4, l = 2, ml = -2, ms = +1/2
B. The n = 1 shell of any given atom can accomodate up to 2electrons.
C. The n = 4 shell of any given atom can accomodate up to 16electrons.
D. In any given atom, the l = 2 subshell can accomodate up to 5electrons that have negative spins (ms =

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CHEM 103 Lecture Notes - Lecture 6: Magnesium Carbonate, Chemical Formula, Electric Light

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