Ms. Francois' AP Chem Classmsfrancoisapchem.weebly.com/uploads/1/3/2/3/13234383/... · Web...

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2.1 Class Work

Sample Question

Explanation of Answer

1. Which sequence represents a correct order of historical developments leading to the modern model of the atom

(1) the atom is a hard sphere most of the atom is empty space electrons exist in orbitals outside the nucleus

(2) the atom is a hard sphere electrons exist in orbitals outside the nucleus most of the atom is empty space

(3) most of the atom is empty space electrons exist in orbitals outside the nucleus most of the atom is empty space

(4) most of the atom is empty space the atom is a hard sphere electrons exist in orbitals outside the nucleus

KEY WORDS AND SYMBOLS:

EXPLANATION:

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2. Which statement correctly describes the charge of the nucleus and the charge of the electron cloud of an atom?

(1) The nucleus is positive and the electron cloud is positive.

(2) The nucleus is positive and the electron cloud is negative.

(3) The nucleus is negative and the electron cloud is positive.

(4) The nucleus is negative and the electron cloud is negative.


EXPLANATION:

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3. According to the wave-mechanical model of the atom, electrons in an atom

(1) are mostly likely found in the excited state

(2) have a positive charge

(3) are located in orbitals outside the nucleus

(4) travel in defined circles


EXPLANATION:

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2.1 Class Work

Which of the following conclusions can be drawn from J. J. Thomson's cathode ray experiments?

(A) Atoms contain electrons.

(B) Practically all the mass of an atom is contained in its nucleus.

(C) Atoms contain protons, neutrons, and electrons.

(D) Atoms have a positively charged nucleus surrounded by an electron cloud.

Which of the following is a correct interpretation of the results of Rutherford's experiments in which gold atoms were bombarded with alpha particles?

(A) Atoms have equal numbers of positive and negative charges.

(B) Electrons in atoms are arranged in shells.

(C) Neutrons are at the center of an atom.

(D) The positive charge of an atom is concentrated in a small region.

Which of the following are true about the Millikan oil drop experiment?

I. Positively and a negatively charged plates were used to hold oil droplets in the air.

II. X rays were used to charge the oil droplets with electrons.

III. This experiment is famous for discovering the density of electrons

A) I only

B) I and III only

C) I and II only

D) II and III only

The person who first postulated the concept of the nuclear atom was

A) Bohr B) DaltonC) Moseley D) Rutherford

Rutherford's alpha–particle bombardment of gold foil helped develop our current model of the atom by determining

A) the existence of the neutronB) that the electron carries a negative chargeC) the existence of electron orbitalsD) that the atom has a concentrated central mass

Which of the following was NOT a conclusion of Rutherford's gold foil alpha particle bombardment experiments?

A) Atoms consist mostly of empty space.

B) Some alpha particles were deflected at large angles.

C) Atoms contain neutrons.

D) Almost all of an atom's mass is located in the nucleus.

2.1 Class Work

Answer the following questions

1. Which statement best describes electrons?

(1) They are positive subatomic particles and are found in the nucleus.

(2) They are positive subatomic particles and are found surrounding the nucleus.

(3) They are negative subatomic particles and are found in the nucleus.

(4) They are negative subatomic particles and are found surrounding the nucleus.

2. Which particles are found in the nucleus of an atom?

(1) electrons, only

(2) neutrons, only

(3) protons and electrons

(4) protons and neutrons

3. Which statement is true about the charges assigned to an electron and a proton?

(1) Both an electron and a proton are positive.

(2) An electron is negative and a proton is positive.

(3) An electron is positive and a proton is negative.

(4) Both an electron and a proton are negative.

4. Which statement is true about a proton and an electron?

(1) They have the same masses and the same charges.

(2) They have the same masses and different charges.

(3) They have different masses and the same charges.

(4) They have different masses and different charges.

5. Which subatomic particle will be attracted by a positively charged object?

(1) proton

(2) neutron

(3) electron

(4) positron

6. Which two particles have approximately the same mass?

(1) proton and neutron

(2) proton and electron

(3) neutron and electron

(4) neutron and positron

2.1 Class Work

John Dalton was an English scientist who proposed that atoms were hard, indivisible spheres. In the modern model, the atom has a different internal structure.

a) Identify one experiment that led scientists to develop the modern model of the atom?

b) Describe this experiment.

c) State one conclusion about the internal structure of the atom, based on this experiment.

In the modern model of the atom, each atom is composed of three major subatomic (or fundamental) particles.

a) Name the subatomic particles contained in the nucleus of the atom

b) State the charge associated with each type of subatomic particle contained in the nucleus of the atom.

c) What is the net charge of the nucleus?

2.1 Class Work

One model of the atom states that atoms are tiny particles composed of a uniform mixture of positive and negative charges. Scientists conducted an experiment where alpha particles were aimed at a thin layer of gold atoms.

Most of the alpha particles passed directly through the gold atoms. A few alpha particles were deflected from their straight-line paths. An illustration of the experiment is shown below.

a) Most of the alpha particles passed directly through the gold atoms undisturbed. What evidence does this suggest about the structure of gold atoms?’

b) A few of the alpha particles were deflected. What does this evidence suggest about the structure of the gold atoms?

c) How should the original model be revised based on the results of this experiment?

2.2 Class Work

Sample Question


Which sequence represents a correct order of What is the total number of neutrons in an atom of an element that has a mass number of 19 and an atomic number of 9?

(1) 9

(2) 19

(3) 10

(4) 28


EXPLANATION:

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A neutral atom contains 12 neutrons and 11 electrons. The number of protons in this atom is

(1) 1

(2) 11

(3) 12

(4) 23


EXPLANATION:

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What is the total number of electrons found in an atom of sulfur?

(1) 6

(2) 8

(3) 16

(4) 32


EXPLANATION:

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In which list are the elements arranged in order of increasing atomic mass?

(1) Cl, K, Ar

(2) Fe, Co, Ni

(3) Te, I, Xe

(4) Ne, F, Na


EXPLANATION:

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2.2 Class Work

Fill in the missing items in the table provided below.

Name of Element

Symbol of Element

Atomic #

Mass #

# Protons

# Electrons

# Neutrons

Na

17

Potassium

P

53

Silver

36

W

29

49

Practice Problems

1. How many protons and electrons are present in a vanadium atom?

2. How many protons, electrons, and neutrons are present in a platinum atom?

3. What is the name of the element that has atoms that contain 5 protons?

4. What is the name of the element that has atoms that contains 82 protons?

5. What is the atomic number of the element that has 74 protons? What is the name of that element?

2.2 Class Work

Sample Question


The nucleus of an atom of cobalt-58 contains

(1) 27 protons and 31 neutrons





EXPLANATION:

2. The nucleus of an atom of 42K contains






EXPLANATION:

Atoms of 16O, 17O, and 18O have the same number of

(1) neutrons but a different number of protons

(2) protons but a different number of neutrons

(3) protons but a different number of electrons

(4) electrons but a different number of protons


EXPLANATION:

Which symbols represent atoms that are isotopes of each other?

(1) 14C and 14 N

(2) 16O and 18 O

(3) 131 I and 131 I

(4) 222Rn and 222 Ra


EXPLANATION:

2.2 Class Work

For each of the following isotopes, write the number of protons, neutrons, and electrons as well as the other notation specified.

Nitrogen-15

Nitrogen-20

# of protons

# of electrons

# of neutrons

S-23

S-25

# of protons

# of electrons

# of neutrons

238 92 U

235 92 U

# of protons

# of electrons

# of neutrons

14N

12N

# of protons

# of electrons

# of neutrons

Describe, in terms of subatomic particles found in the nucleus, one difference between the nuclei of carbon- 12 atoms and the nuclei of carbon-13 atoms. The response must include both isotopes.

Describe, in terms of subatomic particles found in the nucleus, one difference between the nuclei of Chlorine-35 atoms and the nuclei of Chlorine-37 atoms. The response must include both isotopes.

2.2 Class Work

Which of the following represents a pair of isotopes?

Atomic Number

Mass Number

(A)

I.

6

14

II.

7

14

(B)

I.

6

7

II.

14

14

(C)

I.

6

14

II.

14

28

(D)

I.

7

13

II.

7

14

What is the difference between the isotopes of bromine Br-79 and Br-81?

A) Atomic charge

B) Number of valence electrons

C) Number of electron shells occupied

D) Number of neutrons

E) Electronegativity

Two isotopes of uranium are U-237 and U-238. Both would be expected to have the same

A) mass B) number of protons C) decay mode D) number of neutrons E) half-life

Which of the following is NOT the same for isotopes of the same element?

A) Mass numberB) Atomic numberC) Number of protonsD) Number of valence electronsE) Number of occupied electron shells in the ground state

Which of the following represents 2 isotopes of the same elements?

DO NOT LEAVE CLASS WITHOUT YOUR DAILY TRACKER CHECKED! Date: _________________ Page 1

“Success is not the result of spontaneous combustion. You must set yourself on fire.”

2.3 Class Work

The accepted values for the atomic mass and percent natural abundance of each naturally occurring isotope of silicon are given in the data table below:

1. Show a correct numerical setup for calculating the atomic mass of Si

2. Determine the total number of neutrons in an atom of Si-29. ______________________________

· To find the average atomic mass, there are 3 simple steps:

Step 1: Determine Relative Natural Abundance

Formula: Percent Natural Abundance / 100

Step 2: Determine Relative Mass

Formula: Relative Natural Abundance x Mass Number

Step 3: Find Average Atomic Mass = Atomic Mass Number

Formula: ADD EACH RELATIVE MASS

2.3 Class Work

· Predict whether you think the answer will be closer to 63 or 65. Explain why.

· The atomic mass of copper is 63.546 amu. Which of copper’s two isotopes is more abundant: copper-63 or copper-65? Explain your reasoning.

· Calculate the atomic mass of copper:

2.3 Class Work

· Calculate the atomic mass. What whole number do you predict it to be close to?

PLEASE SOLVE THIS IN YOUR CORNELL NOTES AS A DOUBLE ENTRY JOURNAL

Naturally occurring elemental carbon is a mixture of isotopes. The percent composition of the two most abundant isotopes is listed below.

• 98.93% of the carbon atoms have a mass of 12.00 atomic mass units.

• 1.07% of the carbon atoms have a mass of 13.00 atomic mass units.

A. Describe, in terms of subatomic particles found in the nucleus, one difference between the nuclei of carbon-12 atoms and the nuclei of carbon-13 atoms. The response must include both isotopes.

B. In the space provided in your answer booklet, show a correct numerical setup for calculating the average atomic mass of carbon.

2.3 Class Work

2.3 Class Work

Calculate the atomic mass of boron

2.4 Class Work

QUESTIONS FOR CHECKS OF UNDERSTANDING:

How many sub-levels may be present in principal energy level 3 (n = 3)? 

How many sub-levels may be present in principal energy level 6 (n = 6)? 

Describe the difference in the definitions of a Bohr orbital and a quantum mechanics orbital.

How many energy levels are used for known atoms?

Which principal energy level holds a maximum of eight electrons?

Which sub-energy level holds a maximum of six electrons?

Which sub-energy level holds a maximum of ten electrons?

In an atom, what is the maximum number of electrons that can have the principal quantum number n = 3?

In an atom, what is the maximum number of electrons that can have the quantum numbers n = 3, l = 2?

In an atom, what is the maximum number of electrons that can have the quantum numbers n = 3, l = 2, ml =  0?

The following set of quantum numbers is not possible: n = 3, l = 2, ml = 0. Explain why not.

The following set of quantum numbers is not possible: n = 2, l = -1, ml = 0. Explain why not.

2.4 Class Work

Advanced Placement Questions: Page 101, #1, 2, 4 and 6



EXPLANATION: My answer to Question # ____ is ______ because…







DO NOT LEAVE CLASS WITHOUT YOUR DAILY TRACKER CHECKED! Date: _________________ Page 17


2.4 Class Work

Advanced Placement Questions: Page 101, #9, 10, 11, 13










2.4 Class Work

Advanced Placement Questions: Page 101, #20, 22, 23









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