Chapter 4 Section Assessment (1-33)
According to Dalton's theory, is it possible to covert atoms of on element into atoms of another? Explain.
Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.
Three isotopes of chromium are chromium-50, chromium-52, chromium-53. How many neutrons are in each isotope, given that chromium has an atomic number of 24?
Chromium-50: 26 neutrons. Chromium-52: 28 neutrons. Chromium-53: 29 neutrons.
How did Dalton advance the atomic philosophy proposed by Democritus?
Dalton advanced Democritus' ideas regarding atoms by creating a scientific theory based on ratios in which elements combine during chemical reactions.
How did Democritus characterize atoms?
Democritus believed that atoms were indivisible and indestructible.
How does the Rutherford model describe the structure of atoms?
In the Rutherford model, the protons and neutrons are located in the nucleus. The electrons are distributed around the nucleus and occupy almost all the volume of the atom.
What equation tells you how to calculate the number of neutrons in an atom?
N=A-Z N=Number of Neutrons A=Mass Number Z=Atomic Number
There are three isotopes of silicon; they have mass numbers of 28, 29, and 30. The atomic mass of silicon is 28.086 amu. Comment on the relative abundance of these three isotopes.
Silicon-28: Most abundant. Silicon-29: Semi-Abundant Silicon-30: Least Abundant
What experimental evidence led Rutherford to conclude that an atom is mostly empty space?
The fact that most of the alpha particles were undeflected by the gold foil was experimental evidence that the atom was mostly empty space.
How do the isotopes of a given element differ from one another?
The isotopes of a given element differ from one another because they contain different amounts of neutrons.
What does the number represent in the isotope platinum-194? Write the symbol for this atom using superscripts and subscripts.
The number 194 represents the mass number. Symbol: 194/78Pt
The element copper has naturally occurring isotopes with mass numbers of 63 and 65. The relative abundance and atomic masses are 69.2% for a mass of 62.93 amu and 30.8% for a mass of 64.93 amu. Calculate the average atomic mass of copper.
63.5 amu.
Calculate the atomic mass of bromine. The two isotopes of bromine have atomic masses and relative abundance of 78.92 amu (50.69%) and 80.92 amu (49.31%).
79.91 amu.
What makes the periodic table such a useful tool?
A periodic table allows you to easily compare the properties of one element to another element.
What are the charges and relative masses of the three main subatomic particles?
A proton has a charge of 1+, an electron has a charge of 1-, and a neutron has a charge of 0. The relative masses of a proton, neutron, and an electron are 1, 1, and 1/1840, respectively.
List the number of protons, neutrons, and electrons in each pair of isotopes. A.) 6/3L, 7/3L B.) 42/20Ca, 44/20Ca C.) 78/34Se, 80/34Se
A.) - Lithium-6 : 3 protons, 3 electrons, and 3 neutrons. - Lithium 7: 3 protons, 3 electrons, and 4 neutrons. B.) - Calcium-42: 20 protons, 20 electrons, and 22 neutrons. - Calcium-44: 20 protons, 20 electrons, and 24 neutrons. C.) - Selenium-78: 34 electrons, 34 electrons, and 44 neutrons. - Selenium-80: 34 protons, 34 electrons, and 46 neutrons.
Complete the table.
A.) 19 B.) B C.) 5 D.) 5 E.) 16 F.) 16 G.) 23 H.) 23
Use Table 4.2 to express the composition of each atom in shorthand form. A.) Carbon-12 B.) Fluorine-19 C.) Beryllium-9
A.) 6 protons, 6 electrons, and 6 neutrons. B.) 9 protons, 9 electrons, and 10 neutrons. C.) 4 protons, 4 electrons, and 5 neutrons.
How many neutrons are in each atom? A.) 16/8 O B.) 32/16 S C.) 108/47 Ag D.) 80/35 Br E.) 207/82 Pb
A.) 8 B.) 16 C.) 61 D.) 45 E.) 125
How many protons and electron are in each atom? A.) Fluorine B.) Calcium C.) Aluminum
A.) 9 protons and 9 electrons. B.) 20 protons and 20 electrons. C.) 13 protons and 13 electrons.
In your own words, state the main ideas of Dalton's atomic theory.
All matter is composed of atoms, which are extremely tiny. All atoms of a given element are identical. Compounds are formed by the chemical combination of two or more different kinds of atoms. A chemical reaction involves joining, separating, or rearranging atoms.
The atomic masses of elements are generally not whole numbers. Explain why.
Atomic mass units are generally not whole numbers because they represent a weighted average that reflects both the mass and the relative abundance of the isotopes as they occur in nature.
Name two elements that have properties similar to those of the element calcium (Ca).
-Barium. -Strontium.
Describe the range of the radii of most atoms in nanometers (nm).
0.2 nm.
A sample of copper with a mass of 63.5 g contains 6.02 X 10^23 atoms. Calculate the mass of a single copper atom.
1.05 X 10^-22 g Cu
Three isotopes of oxygen are oxygen-16, oxygen-17, oxygen-18. Write the symbol for each, including the atomic number and mass number.
16/8O 17/8O 18/8O Atomic number is 8.
Boron has two isotopes: boron-10 and boron-11. Which is more abundant, given that the atomic mass of boron is 10.81 amu?
Boron 11 is more abundant because given the atomic mass of boron is 10.81 amu, which is closer to 11. This means that there is more abundant % of boron-11.
Compare Rutherford's expected outcome of the gold-foil experiment with the actual outcome.
Rutherford's expected outcome based on Thomson's plum-pudding model was that the alpha particles were supposed to be completely deflected. Instead, most of the alpha particles went through the foil undeflected and very few were deflected.
What distinguishes the atoms of one element from the atoms of another?
The number of protons distinguishes the atoms of one element from those of another.
What instrument can be used to observe individual atoms?
The scanning tunneling microscope is the instrument used to observe individual atoms.
What are three types of subatomic particles?
The three types of subatomic particles are protons, neutrons, and electrons.
Describe Thomson's and Milikan's contributions to atomic theory.
Thomson discovered the electron with his cathode ray tube experiment. Millikan determined the quantity of charge for an individual electron.
How did Rutherford's model of the atom differ from Thomson's?
Thomson plum-pudding model was that electrons were stuck inside a mass of uniform positive charge. Rutherford's model was that all of the positive charge and most of the mass was concentrated in a tiny nucleus and that electrons circle the nucleus and occupy most the the atom's volume.
How is the atomic mass calculated?
To calculate the atomic mass of an element, multiply the mass of each isotope by its natural abundance, expressed as a decimal, and then add the products.
