Physical Science Final Part 3

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Which are older, the atoms in the body of an elderly person or those in the body of a baby?
They are the same age, which is appreciably older than the solar system
Which of the following statements best describes an element?
a material consisting of only one type of atom
The element bromine, Br (atomic number 35), has two major isotopes of similar abundance, both around 50 percent. The atomic mass of bromine is reported in the periodic table as 79.904 atomic mass units. Choose the most likely set of mass numbers for these two bromine isotopes.
Br-79, Br-81
Which contributes more to an atom's mass: electrons or protons? Which contributes more to an atom's size?
protons contribute more to an atom's mass while electrons contribute more to its size
Why isn't dirt listed in the periodic table?
the periodic table lists only elements made of one kind of material. Dirt is a mixture of elements and compounds.
What happens to the properties of elements across any period of the periodic table?
the properties of the elements gradually change across any period of the periodic table
Strontium, Sr (number 38), is especially dangerous to humans because it tends to accumulate 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
What is the main difference between a conceptual model and a physical model?
a physical model represents the shape and form while a conceptual model describes how a system behaves
How would you describe light generated by heating pure elements if it was observed through a prism or spectroscope?
you would see a series of very sharp lines of emitted light
How is the term photon related to the term quantum?
a quantum is a particle of light while a photon is a wave of light
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
How is it possible to deduce the identity of an element from its electron configuration?
if the atom is electrically neutral, the number of electrons corresponds to the atoms atomic number
Which beam is due to alpha particles? (a curves up, b straight, c curves down)
c
Which of the following statements best describes the strong nuclear force?
the force is very strong but has a very short range
Which of the following statements about electrons is true?
has a negative charge, behave like waves, particles, and can be excited by light energy
What property of half-lives makes radioactive material so problematic?
there is no known way to shorten a half-life and radioactivity is limited by the natural decay-time to stable isotopes
The half-life of carbon-14 is 5,730 years. A sample is found to have one-eighth the original amount of carbon-14 in it. How old is the sample.
17,200
Which of the following statements about chain reactions is true?
the key requirement for a chain reaction is that more neutrons are produced than are absorbed
Which of the following elements is the most stable from a nuclear point of view?
iron
Where does the earth receive most of its energy?
external fusion
Is chemistry the study of the submicroscopic, the microscopic, the macroscopic, or all three?
All, because most everything is made of atoms and molecules
A TV screen looked at from a distance appears as a smooth continuous flow of images. Up close, however, we see this is an illusion. What really exists are a series of tiny dots (pixels). This is similar to a chemist's view of matter in that
on the submicroscopic level, chemists find that matter is made of extremely small particles such as atoms and moelcules
A sample of iron weighs more after it rusts because
of the additional oxygen it contains
Oxygen atoms are used to make water molecules. Does this mean the oxygen, O2, and water, H2O, have similar properties?
no, compounds are uniquely different from the elements from which they're made
What is the valence shell?
it is the outermost shell of electrons in an atom
The concept of a chemical bond is ____.
how two or more atoms are held together
What is the correct electron dot structure for carbon?
one dot on each side
How many valence electrons does boron (B, atomic number 5) have?
3
How do the electron-dot structures of elements in the same group in the periodic table compare with one another?
elements of the same group have the same number of valence electrons
What is the name for the following polyatomic ion? (CH3CO2-1)
acetate
If you mix a typical aluminum ion (Al #13) with a typical oxygen ion (O #8) what compound is formed?
Al2O3
Which of the following describes how metal atoms behave in a bulk metallic object?
the metal ion shares its outermost electrons freely with its neighbors
What is the main difference between an ionic and covalent bond?
one is the sharing of a pair of electrons, the other is the transfer of at least one electron
Which of the following substances is pure?
a covalent compound consisting of one type of molecule, an ionic compound consisting of sodium and chlorine ions, and an element
Does an ionic bond have a dipole?
yes, the ionic bond is an example of a very strong dipole
Atoms of nonmetallic elements form covalent bonds, but they can also form ionic bonds. How is this possible?
an ionic bond results when a nonmetallic element gains an electron from a metallic element
What is the difference between a compound and a mixture?
a mixture can be physically separated into its components and a compound cannot be physically separated into its components
Which of the following is a pure substance?
baking soda
How are intermolecular forces and solubility related?
solubility depends on the solvents ability to overcome the intermolecular forces in a solid
In a solution made from one teaspoon of sugar and one liter of water, which is the solute?
sugar
Which of the following statements describes a saturated solution?
a solution of salt water with salt at the bottom, a carbonated beverage with bubbles, and a solution where the solvent cannot dissolve any more solute
Which of the following solutions is the most dilute?
They are all the same
What statement best describes a mole?
it is a very large number chemists use to count atoms or molecules
How many molecules of sucrose are in 0.5 L of a 1 molar solution of sucrose?
3.01 x 10^23 molecules of sucrose
How can you tell whether a sugar solution is saturated or not?
cool the solution to see if there is a precipitate