AnswersTN-Physical Science SC 26-27 For CreditAtomic Theory

Atomic Theory — Unit test Answers

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1
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Which have different numbers of electrons?

A
different ions of an element
B
different isotopes of an element
C
the nucleus of an element
D
each of the atoms of an element
2
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This is how manganese appears in the periodic table.

Question illustration
A
period symbol of manganese
B
isotope symbol of manganese
C
group symbol of manganese
D
chemical symbol of manganese
3

While looking at bromine (Br) on the periodic table, a student needs to find another element with very similar chemical properties but with a different atomic mass. Which best describes the student’s options?

A
There are two possible elements, and they are directly to the left and right of bromine.
B
There are two possible elements, and they are directly above and below bromine.
C
There are many possible elements, and they are all in the same vertical column as bromine.
D
There are many possible elements, and they are all in the same horizontal row as bromine.
4

An atomic physicist determines that an atom is composed of 8 positively charged particles and has a mass of 15 amu. Which is the best conclusion that can be drawn?

A
The atom has 7 neutrons and 8 protons.
B
The atom has 7 electrons and 8 protons.
C
The atom has 8 neutrons and 7 electrons.
D
The atom has 8 electrons and 7 protons.
5

The model below shows an atom of an element.

Question illustration
A
6
B
8
C
9
D
16
6

The atomic number of beryllium (Be) is 4, and the atomic number of barium (Ba) is 56. Which comparison is best supported by this information?

A
They are in the same group because they have similar atomic masses, but they are in different periods because they have different chemical properties.
B
They are in the same group because they have similar chemical properties, but they are in different periods because they have very different atomic numbers.
C
They are in the same group because their atomic numbers are each multiples of four, but they are in different periods because they have different chemical properties.
D
They are in the same group because they have similar atomic masses, but they are in different periods because they have very different atomic numbers.
7

Particle A has very little mass in comparison to Particle B. Both particles are in the same atom. Which is the best conclusion about Particles A and B?

A
They have the same charge.
B
They are located in the nucleus together.
C
Particle A has a positive charge, and Particle B is neutral.
D
Particle A orbits the nucleus, and Particle B is located in the nucleus.
8

What is an atomic nucleus?

A
the outer part of an atom in which electrons move
B
the outer part of an atom in which neutrons move
C
the central part of an atom, composed of protons and neutrons
D
the central part of an atom, composed of protons and electrons
9

Who was the first chemist to organize elements by atomic number?

A
Johann Wolfgang Döbereiner
B
Antoine Lavoisier
C
Henry Moseley
D
John Newlands
10

What is the electron configuration for helium (He)?

A
1s1
B
1s2
C
1s22s1
D
1s22s2
11

Which shows the electron configuration for Silicon (Si)?

A
[Ar]4s23d104p4
B
[Ar]3d14s2
C
[Ne]3s23p4
D
[Ne]3s23p2
12

Students are completing a table about a particular subatomic particle that helps make up an atom.What best explains how they should complete the table?

Question illustration
A
with “Inside the nucleus,” because the particle is a proton
B
with “Inside the nucleus,” because the particle is a neutron
C
with “Outside the nucleus,” because the particle is a proton
D
with “Outside the nucleus,” because the particle is an electron
13

Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below.

Question illustration
A
A few of the positive particles aimed at a gold foil seemed to bounce back off of the thin metallic foil.
B
Experiments with water vapor showed that elements combine in specific proportions.
C
Equations were used to identify regions around the nucleus where electrons would likely be.
D
Cathode rays were bent in the same way whenever a magnet was brought near them.
14

An atom of the element chromium has an atomic number of 24 and a mass number of 52. How many electrons are in an uncharged atom of chromium?

A
0
B
24
C
28
D
52

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