Gen. chem exam 1

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1

A pure substance composed of 2 or more different elements is a_____.

Chemical compound

2

Who is credited with measuring the mass charge ratio of an element?

J.J. Thompson

3

The Chemist credited for inventing a set of symbols for writing the formulas of a compound, and for discovering selenium, silicon, and thorium is _______.

Jöns Jacob Berzelius

4

The law of multiple proportions states that________________.

if multiple compounds can form from the same 2 elements, and the mass of one element is fixed, then the masses of the other element occur in small whole number ratios.

5

Mass fraction=

(Total mass of element in compound)/(Total mass of compound)

6

Which of the following postulates of Dalton's atomic theory are still scientifically accepted?

I.

All atoms of the same element are identical.

II.

Compounds are combinations of different atoms.

III.

A chemical reaction changes the way atoms are grouped together.

IV.

Atoms are indestructible.

II and III

7

T/F: The emission spectrum of hydrogen contains a continuum of colors.

False

8

Excited hydrogen atoms radiate energy in the___________.

infrared, visible and ultraviolet regions.

9

Which of the following statements are false?

I.

It takes less energy to add an electron to nitrogen than to carbon because nitrogen

will be closer to achieving a noble gas configuration.

II.

It takes more energy to add an electron to fluorine than to oxygen because the radius

of fluorine is smaller and more repulsion would occur in the p-orbitals.

III.

It takes more energy to add an electron to nitrogen than to carbon because of the

extra repulsions that would occur in the 2p orbitals.

IV.

Less energy is released in adding an electron to iodine than to chlorine because

the radius of iodine is larger and the electron is added at a distance further

from the nucleus.

I, II

10

What type of spectrum, if any, would be produced if the light radiated by a heated atomic gas were to be dispersed through a prism?

Discrete lines of different colors

11

T/F: A 2p orbital is more penetrating than a 2s; i.e., it has a higher electron density near the nucleus and inside the charge cloud of a 1s

False

12

The 2s orbital in calcium is more stable (more negative energy) than the 2p orbital even though the 2p orbital has its maximum electron density closer to the nucleus. The reason for this higher stability is:

due to its greater penetration, the 2s orbital has more electron density close to the nucleus than the 2p orbital

13

According to the Aufbau principle which sublevel is filled after the 5s sublevel?

4d

14

The Aufbau principle states that___________________.

electrons orbiting one or more atoms fill the lowest available energy levels before filling higher levels.

15

How many unpaired electrons are there in a manganese atom?

5

16

Ionization energy is_____________.

the energy required to remove an electron from a neutral atom.

17

Electron affinity is____________.

the energy change when a neutral atom attracts an electron to become a negative ion

18

Electronegativity is_______________.

the ability of an atom in a molecule to draw bonding electrons to itself.

19

T/F: Subshell energies are higher in multielectron atoms than the same subshell in the hydrogen atom.

False

20

T/F: In the hydrogen atom, all subshells of a principal shell are at the same energy level.

True

21

T/F: In a multielectron atom, the various subshells of a principal shell are at different energy levels.

True

22

T/F: All orbitals within a subshell of a multielectron atom are at the same energy level.

True

23

T/F: In high numbered principal shells of a multielectron atom, some subshells of different principal shells have nearly identical energies.

True

24

What is the maximum number of electrons that can occupy the n = 5 shell?

50

25

How many orbitals are there of the 4f type?

7

26

Areas of zero probability of finding an electron are called _________.

nodes or nodal surfaces

27

The statement that "the lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli principle in a particular set of degenerate orbitals" is known as___________.

Hund's rule

28

Which of the following atoms or ions has three unpaired electrons?

N

29

Which of these pairs is incorrect?

gallium - main group nonmetal

30

Which one of the following equations correctly represents the process involved in the electron affinity of X?

X(g) + e¯ → X¯(g)

31

Which of the following statements is true?

The ionic radius of Fe+ is larger than that of Fe3+.

32

Which of the following compounds has the greatest bond polarity?

HF

33

Consider the following elements: Si, Co, Cl, P, Sr, F, Rb
Select the most accurate statement.

Co, Sr, and Rb will form ionic compounds with Cl and F

34

In the reaction between magnesium and sulfur, the magnesium atoms

become cations

35

Give the name and formula of the compound whose molecules consist of two iodine atoms and seven oxygen atoms.

diiodine heptaoxide; I2O7

36

Using the following bond energies:

Bond Bond Energy (kJ/mol) C≡C 839 C–H 413 O=O 495 C=O 799 O–H 467 estimate the heat of combustion (ΔE) for one mole of acetylene: C2H2(g) + 5/2O2(g) → 2CO2(g) + H2O(g)

–1228 kJ

37

In the cyanide ion (CN), the nitrogen has a formal charge of

0