HW #10 CH 12
If an element has 9 protons and 10 neutrons and 9 electrons, which expression correctly identifies the element?
19F9
Which of the following best describes a conceptual model of an atom?
A model that illustrates the tendency of an atom to undergo chemical bonding
How is the term photon related to the term quantum?
A quantum of light is actually one photon.
What does the following element description actually mean? 238U92
A uranium atom with 92 protons and 146 neutrons
When a rainbow of colors of light are combined into a single ray it forms
white
Which of the following elements are in the same group as silicon (Si)?
B. C
A beam of protons and a beam of neutrons of the same energy are both harmful to living tissue. The beam of neutrons, however, is less harmful. Why?
Neutrons carry no electric charge and thus have a greater likelihood of passing through the tissue.
The shell model presented in this book is not very accurate. Why then is it presented?
The shell model is simpler and easy to understand.
Should the periodic table be memorized? Why or why not?
No. The periodic table is a reference to be used, not memorized.
According to the shell model, which electrons play the most significant role in determining the properties of an atom?
Those in the outermost shell.
Which of the following is not a nonmetal?
Titanium (atomic no. = 54)
In what sense can you truthfully say that you are part of every person around you?
We are continually exchanging our atoms.
Why can't we see atoms?
We see with light energy and the wavelength is larger than the object and so it is not reflected.
How does the wave model of electrons orbiting the nucleus account for the fact that the electrons can have only discrete energy values?
When an electron wave is confined, it is reinforced only at particular frequencies.
How many electrons are there in the third shell of sodium, Na (atomic number 11)?
One.
Which of the following could not be represented by a conceptual model?
The floor plan of a house.
An element is best described as a material
consisting of only one type of atom.
The _______ represents the complete range of frequencies of light energy from the radio waves to cosmic rays.
electromagnetic spectrum.
Suppose that a certain atom possesses only four distinct energy levels. Assuming that all transitions between levels are possible, how many spectral line will this atom exhibit?
six
A cat strolls across your backyard. An hour later, a dog with its nose to the ground follows the trail of the cat. Explain what is going on from a molecular point of view.
The dog is smelling molecules from the cat.
The following statement describes which subatomic particle best? "It is electrically charged"
A and B (A. an electron & B. a proton)
How might the spectrum of an atom appear if its electrons were not restricted to particular energy levels?
A broad spectrum of all colors would be observed.
What is the approximate mass of a carbon atom in atomic mass units (amu)? How about a carbon dioxide molecule?
A carbon atom has a mass of about 12 amu. Carbon dioxide would then have a mass of 44 amu.
Which of the following elements is an alkali metal?
Lithium (Li)
If a neutral element has the following chemical symbol, how many electrons does it have? 18O6
6
The isotope lithium-7 has a mass of 7.0160 atomic mass units, and the isotope lithium-6 has a mass of 6.0151 atomic mass units. Given the information that 92.58 percent of all lithium atoms found in nature are lithium-7 and 7.42 percent are lithium-6, calculate the atomic mass of lithium, Li (atomic number 3).
6.942 amu
An atom absorbs or emits only particular frequencies of light. White light bends into a glass prism and separates into a rainbow of colors. In which of these two scenarios does the electromagnetic radiation behave as a wave? As a particle?
Absorption of light shows particle behavior while bending of light shows wave behavior.
What do the components of a conceptual model have in common?
All components interact with each other.
Which of the following is a property of light?
All of the above. (A. Its energy comes in packets of uniform size. (B. It is a wave. (C. It is a particle.
Which of the following best explains what is happening when an atom emits light?
An electron is dropping from a higher to a lower energy level with the difference in energy between the two being emitted as light.
Which element would have chemical properties the most similar to chlorine (Cl)?
Br
Which of these properties describes a metal?
Conducts heat very well.
What is a valence shell?
It is the outermost shell of electrons in an atom.
Which element has the atomic number 9?
F
Helium, He, is a nonmetallic gas and the second element in the periodic table. Rather than being placed adjacent to hydrogen, H, however, helium is placed on the far right of the table because
Helium is most similar to other group 18 elements.
What does the following element description actually mean? "Iron-57"
Iron with a mass number of 57.
Would you use a physical model or a conceptual model to describe the following: a gold coin, dollar bill, car engine, air pollution, virus, spread of sexually transmitted disease?
Physical model - gold coin, car engine, virus; Conceptual model - air pollution, spread of sexually transmitted disease; dollar bill, which could represent wealth, may well be described by either model
If you remove two protons and two electrons from a sulfur atom (S), what new element is formed?
Si
An element has two different isotopes: one that weighs 65 amu and another that weighs 67 amu. If the average atomic mass of all the isotopes is 66.5 amu, what can be said about the relative abundance of the isotopes?
The isotope with the mass of 67 is more abundant than the isotope with the mass of 65.
Evidence for the existence of neutrons did not come until many years after the discoveries of the electron and the proton. Give a possible explanation.
The neutron lacks an electrical charge.
What subatomic particle by itself is least affected by electromagnetic radiation?
The neutron.
Oxygen, O, (number 8), sulfur, S, (number 16), and selenium, Se, (number 34) have such similar chemical properties because
Their outermost shells contain the same number of electrons.
Does it make sense to say that a textbook is about 99.9 percent empty space?
Yes. A textbook like all material things is made up of atoms, which are considered to be 99.9 percent empty space.
Which of the following elements is a gas at room temperature?
argon (Ar)
If an element has 18 protons and 20 neutrons and 18 electrons, which expression correctly identifies the element?
argon-38
If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element?
atomic mass, 99 amu; Technetium
Which of the following elements is in the fourth period?
chromium (Cr)
Which of these does not describe a metal a room temperature?
gas
Strontium, Sr (number 38), is especially dangerous to humans because it tends to accumulate in calcium-dependent bone marrow tissues (calcium, Ca, number 20). This fact relates to the organization of the periodic table in that strontium and calcium are both
in group 2 of the periodic table.
The oldest known elements in the periodic table are the ones with
odd looking atomic symbols
