Unit 5 - Chemical compounds
An elemental metal contains how many types of atoms?
1
How many fluorine atoms are in the correct formula for hydrofluoric acid?
1
How many hydrogen atoms are in the correct formula for hydrobromic acid?
1 hydrogen atom - The correct formula is HBr. This is a simple binary acid in which the prefix hydro- is added before the name of the anion, with its ending changed to -ic. Bromine (Br-) is then the anion, with an oxidation state of 1-, so one hydrogen (H+) is required to balance the charge.
How many oxygen atoms are in the correct formula the ionic compound formed by the lithium cation, Li+, and the oxygen anion, O2−?
1 oxygen atom - The correct formula is Li2O. The lithium cation exhibits a charge of 1+, while the oxygen anion exhibits a charge of 2-. Thus, it takes two Li1+ ions to form a neutral compound with one O2- ion.
How many electrons are transferred in the following compound: BaO?
2
How many copper atoms are in the correct formula for the compound copper(I) oxide?
2 copper atoms - The correct formula is Cu2O. The Roman numeral (I) after the element copper denotes that the copper ion (Cu+) exhibits a charge of 1+ in this case. Since the oxygen ion (O2-) exhibits a charge of 2-, two Cu+ atoms are required to balance the charge.
What is the oxidation number of calcium?
2+ (Calcium is found in the alkaline earth metals (Group IIA), and has two valence electrons, which it donates to form an ion with a charge of 2+.)
How many hydrogen atoms are in the correct formula for carbonic acid?
2, 2 hydrogen atoms - The correct formula is H2CO3. The acid compound has an -ous ending on the anion, which is used to replace the suffix -ite, so the acid must therefore contain the nitrite ion (NO2-). Two H+ ions are needed to balance the charge
How many atoms of calcium would be needed to get a charge of +6?
3
How many calcium atoms are in the correct formula for calcium phosphide?
3
How many electrons are transferred in the following compound: AlCl3?
3
How many bromine atoms are in the correct formula for the compound lead(IV) bromide?
4, The Roman numeral (IV) after the element lead denotes that the lead ion (Pb4+) exhibits a charge of 4+ in this case. Since the bromine ion (Br-) exhibits a charge of 1-, four Br- ions are required to balance the charge.
Write the names for NH4OH and Al(C2H3O2)3.
Ammonium hydroxide and aluminum acetate
What type of compound is CHCl3, the anesthetic chloroform?
Basic Carbon (group 14) is a nonmetal, hydrogen (group 1) is a nonmetal, and chlorine (group 17) is a nonmetal. Since these are all nonmetals with similar electronegativities which therefore share their valence electrons, CHCl3 is predicted to be covalent.
What is the name of the following compound, which contains a polyatomic ion: BeCrO₄?
Beryllium chromate ( The name of the compound is beryllium chromate. CrO42- is a common polyatomic ion known as chromate, which exhibits a charge of 2-. Beryllium is a metal from Group IIA, which in its ionic form exhibits a charge of 2+. Since the compound is composed of metal and nonmetal ions, it is ionic, and there is therefore no need to designate the charges in its name.)
Compounds containing only two elements are called what?
Binary compounds
Law of Definite Proportions.
Chemical compounds can be represented in an abbreviated way using chemical symbols. A formula indicates what chemical elements are present in the compound. Atoms and compounds are neutral and have an equal number of positive and negative charges. When writing formulas the oxidation numbers must add up to zero.
How are ionic and covalent compounds chemically different?
Compounds that contain ions are called ionic compounds. Ionic compounds generally form from metal cations and nonmetal anions. Compounds that do not contain ions, but instead consist of atoms bonded tightly together in molecules (uncharged groups of atoms that behave as a single unit), are called covalent compounds. Covalent compounds usually form from two nonmetals.
The ability to be stretched into long wires is a property of metals known as
Ductility
True or False: All metals have high melting points.
False
True or False: Most metals are found to occur naturally in their uncombined states.
False
What is the formula for the acidic compound hydrochloric acid?
HCl - The chlorine ion exhibits a charge of 1- and hydrogen ion exhibits a charge of 1+.
What is the name of the following compound: HCl?
Hydrogen chloride The compound is named hydrochloric acid. Since the compound contains two nonmetals, one of which is hydrogen, it is an acid. Therefore, we name the element that the hydrogen is attached to and change the ending of that element to -ic. Add "hydro" to the front of the element and add the word "acid" to the end.
What types of elements form ionic bonds? Covalent bonds? Metallic bonds?
Ionic = metals and nonmetals; covalent = nonmetals and nonmetals; metallic = metals and metals.
What type of compound is Fe2O3, and what is its name?
Ionic, iron(III) oxide ( The compound is ionic and is named iron(III) oxide. Because the compound is composed of a transition metal bonded to a nonmetal, it is an ionic compound containing a polyvalent metal and is named as such.)
What type of compound is TiCl4 and what is its name?
Ionic, titanium(IV) chloride The compound is ionic and is named titanium(IV) chloride. Because the compound is composed of a transition metal bonded to a nonmetal, it is an ionic compound containing a polyvalent metal and is named as such.
What diagrams of molecules represent only two dimensions?
Lewis Dot
What is the formula for the ionic compound formed by lithium (Li) and nitrogen (N)?
Li3N
rite the name for Li2
Lithium selenide
What is the name of the following compound, which contains a polyatomic ion: MgSO4?
Magnesium sulfate The name of the compound is magnesium sulfate. SO42- is a common polyatomic ion known as sulfate, which exhibits a charge of 2-. Magnesium is a metal from Group IIA, which in its ionic form exhibits a charge of 2+. Since the compound is composed of metal and nonmetal ions, it is ionic, and there is therefore no need to designate the charges in its name.
What is ductile? Name a metal that is very ductile.
Material can be drawn into thin wire. The most common example is copper, but many other metals are ductile as well.
What does malleable mean? Name a metal that is very malleable.
Material can be hammered into thin sheets. Think about gold, silver, aluminum, or many other metals.
_______. are elements that have a weak hold on their valence electron
Metals
How do the properties of malleability and ductility help you in your daily life?
Metals being ductile and malleable allows them to be shaped and used as wiring, heat conductors, and many other useful items used in our daily lives.
An ion found in some compounds contains 12 protons and 10 electrons. What is its symbol?
Mg2+ Because the number of protons remains unchanged when an atom forms an ion, the atomic number of the element must be 12. Knowing this lets us use the periodic table to identify the element as Mg (magnesium). The Mg atom has lost two electrons and thus has two more positive charges (12) than it has electrons (10). This is the aluminum cation, Mg2+.
What is the formula for the ionic compound magnesium phosphide?
Mg3P2
Predict the formula of the ionic compound formed between the sodium cation, Na+, and the sulfide anion, S2−.
Na2S
Name the following compounds: NF3 and As2O3.
Nitrogen trifluoride and Diarsenic trioxide
What shape does the ammonia molecule have?
One unshared pair of electrons on top that pushes down on the hydrogen bonds to deform the angle of hydrogen to nitrogen into 107 degrees.
What is the name of the following compound, which contains a metal that can exhibit more than one ionic charge: PbCl2?
PbCl2 is ionic and contains two chloride anions, each of which exhibits a charge of 1-, so in order to balance these two negative charges the polyvalent lead cation must in this case exhibit a charge of 2+. Lead(II) Chloride is then the correct name for the compound, with the Roman numeral representing the charge on the lead ion. This can be verified by noting the subscript on the chloride anion, which corresponds to the Roman numeral.
What is the name for the following compound: RbOH?
Rubidium hydroxide The compound is named rubidium hydroxide. Because it contains a metal cation bonded to a hydroxide anion, it is a base. It should therefore be named as such, with the name of the metal cation followed by the name of the anion.
Which metals do you use in your daily life?
Some examples include the copper wiring in your home, the nickel and chromium plated elements on your stove, and the steel frame of your car or bicycle.
what shape does the molecule methane have?
Tetrahedral; no unshared pairs so there is no unequal pushing of electrons on each other and the molecule is symmetrical
Why is it necessary to have more than one atom of Cl in the compound CaCl2?
The calcium ion (Ca2+) has an oxidation state of 2+, while chlorine (Cl1-) has an oxidation state of 1-. Therefore, two Cl1- ions are required to balance the charge with one Ca2+.
What type of compound is CO2?
The compound is covalent. CO2 (carbon dioxide) is composed of two nonmetals with similar electronegativities which therefore share their valence electrons, so it is a covalent compound.
What is the term for how valence electrons act in a metallic bond?
The electrons float from metal atom to metal atom, like in a sea of electrons.
Sometimes molecules with different numbers of atoms share a shape. For example, hydrogen chloride has two atoms and carbon dioxide has three atoms yet they have the same shape. What molecular structure do they both have?
The shape is linear, meaning that the angle between the bonding atoms is 180 degrees.
What purpose do the subscripts serve in a formula?
The subscripts in a formula denote how many atoms of each type are required for the compound to be neutral.
What is the formula for the acidic compound sulfuric acid?
The sulfate ion exhibits a charge of 2- and each hydrogen ion exhibits a charge of 1+.
How are electrons arranged in metallic bonds?
They are delocalized and free-floating.
What kind of electron affinity do metals have?
This means that the valence electrons are held loosely by the metal atoms
The CO molecule has a _______ bond, and the O2 molecule has a _________ bond.
Triple, Double
True or False: Metals are good conductors of heat and electricity.
True
If the central atom in the molecule has valence electrons not used in bonding with other atoms, the electrons are called ________.
Unshared pairs of electrons. Like on the oxygen atom in the water molecule, these unshared pairs act like a force field of negative charge, repelling the electrons contained in the oxygen to hydrogen bonds at the other end of the molecule and creating the bent shape.
List the steps for naming binary ionic and polyatomic compounds.
Write the names of the two substances involved. Change the ending of the second substance to -ide, but leave polyatomics alone.
What is the name of the following compound: XeF4?
Xenon tetrafluoride The compound is named xenon tetrafluoride. The compound is composed of two nonmetals, neither of which is hydrogen, so it is a covalent compound. It should therefore be named using Greek prefixes to designate the number of atoms, and since the first element is a single atom, the prefix mono- is not used.
a neutral calcium atom, with 20 protons and 20 electrons, readily loses two electrons, what does this result in?
a cation with 20 protons, 18 electrons, and a 2+ charge
What is the name of the following compound: CaCO3
calcium carbonate
What is the name of the following compound: Cr(NO3)3?
chromium (3) nitrate
When atoms of nonmetal elements form ions, they....
gain enough electrons to give them the same number of electrons as an atom of the next noble gas in the periodic table.
How are the names of ionic and covalent compounds different?
ionic compounds are named by writing the name of the cation followed by the name of the anion, with the ending of the anion changed to -ide. Covalent compounds are named using Greek numerical prefixes, again with the ending of the anion changed to -ide.
During the formation of some compounds, atoms gain or lose electrons and form electrically charged particles called __________
ions
In chemical reactions, the _________ of each atom (and thus the identity of the element) remains unchanged
nucleus
Which of the following substances would not conduct electricity in any state?
one in which electrons are shared
A _______ represents the number of electrons lost (a positive oxidation number) or gained (a negative oxidation number) by an atom as it is ionized, and is expressed as a superscript
oxidation number
What is the name of the following compound: K3N?
pottasium nitrate
Why do metals bend and not break?
they share electrons in discrete bonds