CHEM 1010

Synthetic sapphire ___. (select all that apply)

-Is produced by heating aluminum oxide powder to very high temperatures -Is denser than glass

Which of the following options correctly describe each type of chemical compound?

-Molecular compounds tend to contain nonmetals only

Which of the following options correctly describe each type of chemical compound?

-Molecular compounds tend to contain nonmetals only. -Nonmetals combine with metals to form ionic compounds.

Nonmetals combine with metals to form ionic compounds.

-O3 is an element -H2o is a compound -Air is a mixture

When an electronic device is recycled, the metals are recovered by ___.

-Treatment with strong acid

Each element in a given compound comprises a fixed percent by ___ of the compound

-mass

Nanotechnology is concerned with science on what scale?

- 1 x 10^-9m

Most elements occur in nature as ___.

-Compounds

In the formation of ionic compounds a nonmetal will __ electrons to form an ion with the same number of electrons as the nearest __ gas.

-Gain; noble

1. Ppm 2. ppb 3.ppt

1. 10^6 2. 10^9 3.10^12

The periodic table is organized such that elements with similar _____properties fall into vertical columns called_____

chemical;groups

Using the periodic table as a guide, specify the number of protons and electrons in a neutral atom of krypton (Kr)

Protons:36 Electrons:36

High-tech devices may save energy because they are more energy efficient when being used, but their production requires more energy because ___. Select all that apply.

-Microprocessors require an energy-intensive process to fabricate -The design process may use a great deal of energy -The diverse materials required to increase cost of production and manufacturing

Solid compounds of metals found in rocks and soil are called ___.

-Minerals

Which of the following options correctly describe each type of chemical compound? Check all that apply

-Molecular compounds tend to contain nonmetals only -Nonmetals combine with metals to form ionic compounds

10mm (millimeters) are equivalent to 1cm (centimeter). To convert 15 cm to mm, you would

-Multiply by 10

Which of the following ion combinations will result in an ionic compound that has a balanced number of positive and negative charges? Select all that apply.

-Na+ and Br- -2Li+ and S2- (note that the 2 is not part of the formula for Li+; the number indicates that 2 Li+ are needed for every 1 S2- ion.) -Ca2+ and 2 F- (note that the 2 is not part of the formula for F; the number indicates the number of F- ions required to bond with 1 Ca2+ ion.)

Classify each element correctly according to its type and/or the group it belongs to

-Ne- noble gas -Cl- halogen -Cu- metal

Match each component of the atom with the correct description

-Nucleus- small region that contains almost all the mass of an atom -Electron- negatively charged particle -Proton- positively charged particle found within the center of the atom -Neutron- uncharged dense particle located in the center of the atom

When balancing a half-reaction, the conservation of mass is reflected by balancing the __on both sides of the equation, while the conservation of charge is reflected by adding __to the appropriate side of the reaction.

-Number of atoms; electrons

Which of the following are allotropes of oxygen?

-O2, O3

Hematite is an iron ore containing Fe2O3. To obtain solid Fe metal from this ore ___. (select all that apply)

-O2- ions will be oxidized (the electrons required to reduce the Fe3+ ion are supplied by the loss of electrons from the O2- ions. -Fe3+ ions must be reduced -The balanced half-reaction is Fe3+ (+) 3e -à Fe

To track the transfer of electrons in both ionic and molecular substances, we assign a(n)—number to each element involved. This number reflects the charge the element would have if all bonds were ionic.

-Oxidation

Match each process with the correct description

-Oxidation-loss of electrons (loss of electrons=oxidation; gain of electrons=reduction) -Reduction-gain of electrons

Many metals occur as minerals in rocks and soil. A mineral in which a metal is bonded to oxygen is called a(n) ___, whereas a mineral containing oxygen and silicon together is called a(n) ___

-Oxide; silicate

Which of the following elements are commonly added to sand when making glass, to improve its thermal properties? Select all that apply.

-Potassium -aluminum -boron

Each element has a unique number of __, which is called the atomic number. For a neutral atom, this number is also equal to the number of __ present.

-Protons; electrons

Silica is a naturally occurring oxide of silicon, SiO2, which is transparent. Pure crystallized Sio2 is known as ___.

-Quartz

The oxidation state of an element ___.

-Reflects its charge if it is present as an ion -Is determined by the way it is bonded -Reflects the way electrons are transferred during a reaction

The number 10,000 can be expressed as 1x10^4. This second form is called ___ notation.

-Scientific

A __ figure is a digit that represents the accuracy with which an experimental quantity is known.

-Significant

Which metals could usefully be recovered from electronic devices? Select all that apply.

-Silver - gold

Managing human consumption of natural resources so that these resources are not exhausted is called __.

-Sustainability

Extracting metals by recycling electronic devices ___.

-Taps into a source that is far more concentrated than metal ores mined from the ground

In which of the following examples has the oxidation number (O.N.) of the given element been assigned correctly? Select all that apply.

-The O.N. for S in SO2 is +4 -The O.N. for iron in FeO is +2

When considering the most responsible end- use of a product, sustainability should take into ___ account. Select all that apply

-The fair distribution of resources -The need to improve the quality of life for all members of society -Environmental aspects such as preventing pollution

An electric current is __.

-The movement of charged particles such as electrons or ions

Which of the following options describe the correct format used when writing the chemical formula of a substance? Select all that apply

-The number of atoms of a particular element is indicated by a subscript -A chemical formula is a symbolic way to represent the composition of a substance

Which of the following options correctly describe the periodic table? Select all that apply.

-The periodic table contains the chemical symbols that represent the elements. -The elements in the periodic table are arranged based on similar chemical properties.

What are the environmental challenges to extracting metals from recycled electronic devices? Select all that apply.

-The solvents used to remove the plastics are not generally environmentally friendly -Contaminated groundwater could contribute to an increase of cancers in surrounding communities -Groundwater could be contaminated with heavy metals

Which of the following statements correctly describe the rules for assigning oxidation numbers (abbreviated as O.N.)? (select all that apply.)

-The sum of the oxidation numbers for the atoms in a neutral compound is zero. -The O.N. for a monatomic ion is the same as its charge.

If a mixture of quartz and bauxite contains 78% quartz, this means that ___.

-There are 78 g of quartz for every 22 g of bauxite -150 g of this mixture contains 117 g of quartz -There are 78 g of quartz in 100 g of the mixture

Which of the following are limitations of the "cradle-to-grave" approach to analysis of consumer goods? Select all that apply.

-This approach assumes that consumer goods will not be recycled -This approached does not encourage sustainable practices

A molecule is an independent structure composed of two or more __ chemically bonded together.

-atoms

which of the following options correctly describe atoms? Select all that apply

-atoms are extremely small -compounds contain two or more different types of atoms -an atom is the smallest unit of an element that can exist as a stable, independent entity.

The molar mass of any substance is the mass of 1 __ of the particles of that substance.

-mol

Which of the following options correctly describe the mass number of an atom? Select all that apply

-the mass number is given by the sum of the protons and neutrons in the nucleus. -The mass number may vary between atoms of a particular element (the mass number can vary since the number of neutrons in the nucleus may vary.)

select the options that correctly reflect the mass ratios and mass percentages of the elements in SO3

-the mass percentage of O is 60.0% -The mass ratio of S is 0.400

Express 105m in terms of nm

1.05x10^11

Rank the following elements correctly according to its number of protons, starting with the element that has the least number of protons at the top of the list.

1.He 2.Al 3.Zn 4.Rn

In the compound MgO, the Mg ion has a charge of ___, while the O ion has a charge of __

-+2; -2

The molar mass of CH2CI2 is 85.0 g/mol, while the molar mass of carbon is 12.0 g/mol. The percent of carbon in this compound is correctly expressed as

-12.0 g C/85.0 g CH2CI2 x 100%

Which of the following reflects the correct procedure to calculate the molar mass of CH2CI2?

-12.0+2(1.0)+2(35.5)=85.0 g/mol

The chemical formula CCl^4 indicates that there is/are ___ carbon atom(s) for every ___ chlorine atom(s).

-1; 4

Express 2.6x10^4 in decimal notation (i.e., as a "regular" number)

-26,000

Which of the following equations represents a reduction half-reaction?

-2H+ (+) 2e- à H2

The correct answer to the mathematical expression 10^16 x 10^14 is 10 ___.

-30; 2

In most modern touchscreens __.

-A conductive object touching the screen distorts the electric field -Layers of conductive wires are sandwiched between insulating surfaces

Which of the following options correctly describe fluxes used in making glass? (select all that apply.)

-A flux lowers the melting point of the sand, thus lowering the temperature required for making the glass -Common fluxes include MgCO3 and CaCO3 -Fluxes make the molten glass less viscous and easier to work

Which of the following statements correctly defines a molecule?

-A molecule is independent structure consisting of two or more atoms chemically bonded together.

An ore is ___.

-A rock containing a significant concentration of a desirable metal

Which of the following statements correctly describe how conversion factors are used in calculations? Select all that apply.

-All units should cancel except for those required for the answer when multiplying by a conversion factor -Conversion factors are relationships used to express the same quantity in different units -The conversion factor should be selected so that the units in the original quantity cancel with one of the units in the factor.

Sapphire is a natural gemstone that is harder than quartz. Sapphire is composed of

-Aluminum oxide

Which of the following are molecular (covalent) compounds? Select all that apply

-CCl4, N2O, SO2

Which of the following formulas for ionic compounds are correct? Select all that apply.

-CaO, Ca3N2 (Silver(Ag) only forms the Ag*ion. Ag* and Cl combine to form AgCl.)

Rare earth metals are used to produce ___. (select all that apply)

-Cell phone speakers -rechargeable batteries -catalytic converters in motor vehicles

Which of the following are rare earth metals? Select all that apply.

-Cerium (Ce) -Gadolinium (Gd)

In the compound CrCl3 ___. (select all that apply)

-Cl has a -1 charge -Cr has a +3 change

In the compound CrCl3 __. (select all that apply)

-Cl has a -1 charge -Cr has a +3 charge

Match each element with the appropriate charge in its ionic form

-Cl: -1 -Sr: +2 -S: -2 -Al: +3

Classify each material according to its ability to enable the flow of electricity

-Conductor- (conductors allow the flow of electricity under all conditions) Gold, Copper, Silver -Semiconductors- (semiconductors include metalloids and certain compounds of containing metals and/or metalloids) CdS, GaAs, Si -Insulators- (do not allow the flow of electricity) concrete, plastic

Match each type of material to the correct description.

-Conductor: enables the flow of electricity -Insulator: does not allow the flow of electricity

An atom of nitrogen (N) has a mass number of 15. This atom (select all that apply)

-Contains 8 neutrons in its nucleus -Contains 7 protons in its nucleus

An approach to analyzing the life cycle of an item, beginning with the raw materials from which it is made to its ultimate disposal, is called the __ approach.

-Cradle-to-grave

An approach to consumer goods that aims at recycling, so that the end of the life cycle of one item leads naturally into the beginning of the life cycle of another, is the ___ approach.

-Cradle-to-grave

Match each type of solid with the correct description.

-Crystal- highly ordered arrangement of constituent particles -Amorphous- disordered/ random arrangement of constituent particles

Which of the following equations represents an oxidation half-reaction?

-Fe2+ à Fe3+ (+) e-

Categorize each type of compound correctly

-Formed when metals combine with nonmetals- ionic -Contains no molecules- ionic -Formed when nonmetals combine- molecular -Composed of molecules- molecular

Copper occurs in a variety of compounds in ores. Chalcocite is a mineral composed of Cu2S. In order to extract solid Cu metal from this ore, the Cu+ ions must ___ electrons and the S2- ions must ___ electrons.

-Gain; lose (each Cu+ ion must gain an electron to form solid metallic Cu. Electrons are supplied by S2- ions.

Match each solid with the correct description

-Glass- random array of silicon and oxygen linkages throughout the solid -Quartz- pure crystallized SiO2 with a highly ordered arrangement at the atomic level

A(n) ___ is a type of chemical equation that shows the electrons either lost or gained by the reactants.

-Half- reaction

Silica glass is made by

-Heating sand to a temperature high enough to melt it and then cooling the liquid until it hardens.

A ___ mixture is uniform throughout, whereas a ___ is not uniform and different components can be distinguished.

-Homogeneous; heterogeneous

Which of the following elements commonly occur as diatomic molecules? Select all that apply.

-Hydrogen (the most common elemental form of hydrogen is H2) -Oxygen (the most common elemental form of oxygen is O2) -Nitrogen (nitrogen's most common elemental form is N2) -Fluorine (fluorine's common elemental form is F2)

Semiconductors ___ (select all that apply)

-Include metalloids such as silicon -Are less conductive than metals -Enable a flow of electricity

Classify each compound correctly as either a covalent or ionic compound

-Ionic compound- NaBr, NiO, FeCl3 -Covalent compound- CO2, PCl3, N2O5

In chemistry, the mole ___. (Select all that apply.)

-Is abbreviated mol -Indicates amount of substance

A material will conduct electricity more readily if ___.

-Its electrons are mobile -The material is made of metal (although metals in their elemental form are conductive)

The accuracy of a calculation is limited by the quantity that has the __ number of significant figures.

-Least

To balance a half-reaction, the number and type of each element present is balanced to reflect the conservation of ___ in the reaction. Electrons are added to the appropriate side of the equation to reflect the conservation of ___.

-Mass; charge

The __ number of an atom is equal to the total number of protons and __ in the nucleus of the atom.

-Mass; neutrons

A conversion factor is the ratio of ___ quantities used to express a quantity in different units of measurement. multiplying by a conversion factor is the same as multiplying a quantity by __ because the numerator and denominator are equivalent.

Equivalent; 1