Concepts of Chemistry, Chapter 3
When atoms other than the noble-gas atoms form bonds, they often have _____________ electrons around them in total.
8 shared
Monatomic anions
Negatively charged particles, such as Cl-, O2-, and N3-, that contain single atoms with a negative charge.
When a metallic atom bonds to a nonmetallic atom, the bond is _____________.
Ionic
What are the Monatomic Cations and how do you name them?
- (name of metal)The names of monatomic cations always start with the name of the metal, sometimes followed by a Roman numeral to indicate the charge of the ion. For example, Cu+ is copper(I), and Cu2+ is copper(II). The Roman numeral in each name represents the charge on the ion and allows us to distinguish between more than one possible charge. Notice that there is no space between the end of the name of the metal and the parentheses with the Roman numeral. If the atoms of an element always have the same charge, the Roman numeral is unnecessary (and considered to be incorrect). For example, all cations formed from sodium atoms have a +1 charge, so Na+ is named sodium ion, without the Roman numeral for the charge. The following elements have only one possible charge, so it would be incorrect to put a Roman numeral after their name. The alkali metals in group 1 are always +1 when they form cations. The alkaline earth metals in group 2 are always +2 when they form cations. Aluminum and the elements in group 3 are always +3 when they form cations. Zinc and cadmium always form +2 cations. • Groups 1, 2, and 3 metals • Al3+, Zn2+, Cd2+, Ag+
Classify each of the following as either a molecular compound or an ionic compound. (Objective 9) a. cadmium fluoride, CdF2 (a starting material for lasers) b. sulfur dioxide, SO2 (a food additive that inhibits browning and bacterial growth)
...CdF2 is ionic and S02 is molecular
Write the name of the group to which each of the following belongs. a. chlorine b. xenon c. sodium d. magnesium
...Chlorine is a halogen, Xenon is a noble gas, Sodium is an Alkali metal, Magnesium is an Alkaline Earth Metal
# of Atoms Prefix 1 mon(o) 2 di 3 tri 4 tetr(a) 5 pent(a) 6 hex(a) 7 hept(a) 8 oct(a) 9 non(a) 10 dec(a)
1 mon(o) 2 di 3 tri 4 tetr(a) 5 pent(a) 6 hex(a) 7 hept(a) 8 oct(a) 9 non(a) 10 dec(a)
Polyatomic ion
A charged collection of atoms held together by covalent bonds.
Molecular compound
A compound composed of molecules. In such compounds, all of the bonds between atoms are covalent bonds.
Ionic Compound
A compound that consists of ions held together by ionic bonds.
Binary covalent compound
A compound that consists of two nonmetallic elements.
Chemical formula
A concise written description of the components of a chemical compound. It identifies the elements in the compound by their symbols and indicates the relative number of atoms of each element with subscripts.
Polar covalent bond
A covalent bond in which electrons are shared unequally, leading to a partial negative charge on the atom that attracts the electrons more and to a partial positive charge on the other atom.
Nonpolar covalent bond
A covalent bond in which the difference in electron-attracting ability of two atoms in a bond is negligible (or zero), so the atoms in the bond have no significant charges.
Double bond
A link between atoms that results from the sharing of four electrons. It can be viewed as two 2-electron covalent bonds
Triple bond
A link between atoms that results from the sharing of six electrons. It can be viewed as three 2-electron covalent bonds.
Lewis structure
A representation of a molecule that consists of the elemental symbol for each atom in the molecule, lines to show covalent bonds, and pairs of dots to indicate lone pairs.
Electron-dot symbol
A representation of an atom that consists of its elemental symbol surrounded by dots representing its valence electrons.
Mixture
A sample of matter that contains two or more pure substances and has variable composition.
Pure substance
A sample of matter that has constant composition. There are two types of pure substances, elements and compounds.
Compound
A substance that contains two or more elements, the atoms of these elements always combining in the same whole-number ratio.
Write the chemical formula for each of the following names. (Objective 28) a. ammonia (a household cleaner when dissolved in water) b. tetraphosphorus hexasulfide (used in organic chemical reactions) c. iodine monochloride (used for organic synthesis) d. hydrogen chloride (used to make hydrochloric acid)
Ammonia is NH3; Tetraphosphorus hexasulfide is P4S6; Iodine monochloride is ICl; Hydrogen chloride is HCl
Chemical bond
An attraction between atoms or ions in chemical compounds. Covalent bonds and ionic bonds are examples.
Binary ionic compound
An ionic compound whose formula contains one symbol for a metal and one symbol for a nonmetal.
An atom or collection of atoms with an overall negative charge is a(n) __________________.
Anion
Classify each of the following as a pure substance or a mixture. If it is a pure substance, is it an element or a compound? Explain your answer. (Objectives 3 & 4) a. apple juice b. potassium (A serving of one brand of apple juice provides 6% of the recommended daily allowance of potassium.) c. ascorbic acid (vitamin C), C6H8O6, in apple juice
Apple juice is a mixture; Potassium is an element -- as it cannot be broken down into a simpler substance; Ascorbic Acid is a compound made up of Carbon, Hydrogen and Oxygen, and with a molecular formula of 6 Carbon atoms : 8 Hydrogen atoms : 6 Oxygen atom. This is the ratio of atoms for each element that comprises Ascorbic Acid.
As in other liquids, the attractions between water molecules are strong enough to keep them the _____________ but weak enough to allow each molecule to be _____________ the attractions that momentarily connect it to some molecules and _____________ to other molecules.
As in other liquids, the attractions between water molecules are strong enough to keep them the same average distance apart, but they are weak enough to allow each molecule to be constantly breaking the attractions that momentarily connect it to some molecules and forming new attractions to other molecules
The ionic compounds barium bromide, silver phosphate, and ammonium iodide are all used in photography. Write the chemical formulas for these compounds. (Objective 37)
BaBr₂,Ag₃PO₄,NH4I
Write chemical formulas for each of the following names. (Objective 37) a. barium chloride (used in manufacture of white leather) b. cobalt(III) oxide (used in coloring enamels) c. manganese(II) chloride (used in pharmaceutical preparations) d. iron(III) acetate (a medicine) e. chromium(III) phosphate (in paint pigments) f. magnesium hydrogen phosphate (a laxative)
BaCl, Co2O3, MnCl2, Fe(CH3COO)3,CrPO4, MgHPO4
Because oxygen atoms attract electrons much more _____________ than do hydrogen atoms, the O-H covalent bond is very polar, leading to a relatively large partial negative charge on the oxygen atom (represented by a(n) ____________) and a relatively large partial positive charge on the hydrogen atom (represented by a(n) _____________).
Because oxygen atoms attract electrons much more strongly than do hydrogen atoms, the O‑H covalent bond is very polar, leading to a relatively large partial minus charge on the oxygen atom (represented by a δ−) and a relatively large partial plus charge on the hydrogen atom (represented by a δ+).
What are the particles that form the basic structure of water? Describe the attraction that holds these particles together. Draw a rough sketch that shows the attraction between two water molecules. (Objective 21)
Because oxygen atoms attract electrons much more strongly than do hydrogen atoms, the O‑H covalent bond is very polar, leading to a relatively large partial minus charge on the oxygen atom (represented by a δ−) and a relatively large partial plus charge on the hydrogen atom (represented by a δ+). attraction between the region of partial positive charge on one water molecule and the region of partial negative charge on another water molecule tends to hold water molecules close together (Figure 3.13). Remember that opposite charges attract each other and like charges repel each other.
Write the most common number of bonds and lone pairs for atoms of each of the following nonmetallic elements. (Objective 13) a. C b. phosphorus c. oxygen d. Br
C forms 4 bonds with 0 lone pairs; Phosphorus forms 3 bonds with 1 lone pair; Oxygen forms 2 bonds with 2 lone pair; Br forms 3 bonds with 1 lone pair
Write the name for each of these chemical formulas. (Objective 37) a. CdI2 (a nematocide—that is, it kills certain parasitic worms.) b. Ca3P2 (in signal flares) c. Au(OH)3 (used in gold plating) d. FeCl2 (in pharmaceutical preparations) e. NH4HSO4 (in hair wave formulations)
Cadium Iodide, Calcium phosphide, Gold Trihydroxide, Iron Chloride, Ammonium Hydrogen Sulphate
An atom or collection of atoms with an overall positive charge is a(n) __________________.
Cation
Write the name for each of the following chemical formulas. (Objective 28) a. ClO2 (a commercial bleaching agent) b. C2H6 (in natural gas) c. HI (when dissolved in water, used to make pharmaceuticals) d. P3N5 (for doping semiconductors)
Chlorine Dioxide; DiCarbonhexahydroxide; Hydrogen MonIodide; Triphosphorus pentanitride
Alcohols
Compounds that contain a hydrocarbon group with one or more -OH groups attached.
Hydrocarbons
Compounds that contain only carbon and hydrogen.
The ionic compounds CuF2, NH4Cl, CdO, and HgSO4 are all used to make batteries. Write the name for each of these compounds. (Objective 37)
Copper Fluoride, Ammonium Chloride, Cadium Oxide, Mercury Sulphate
When a nonmetallic atom bonds to another nonmetallic atom, the bond is _____________.
Covalent
A(n) ______________________ bond is a link between atoms that results from the sharing of two electrons
Covalent Bond
Describe the hydrogen molecule, H2. Your description should include the nature of the link between the hydrogen atoms and a sketch that shows the two electrons in the molecule.
Covalent bonding. Covalent bonding is the sharing of one or more pairs of electrons between 2 nonmetal atoms, so both atoms can achieve a Noble Gas electron configuration. When two H atoms bond to form a hydrogen molecule, both atoms get two electrons, just like a stable helium atom. H• + •H → H:H
A molecule like H2, which is composed of two atoms, is called __________________.
Diatomic
Mixtures are samples of matter that contain two or more pure substances and have _____________ composition.
Each substance in a mixture retains its own chemical identity and hence its own properties. Whereas pure substances have fixed compositions, the compositions of mixtures can vary
Atoms can form double bonds, in which _____________ are shared between atoms. Double bonds are represented by "lines in a Lewis structure."
Electrons
Classify each of the following as a pure substance or a mixture. If it is a pure substance, is it an element or a compound? Explain your answer. (Objectives 3 & 4) a. fluorine (used to make fluorides, such as those used in toothpaste) b. toothpaste c. calcium fluoride, CaF2, from the naturally occurring ore fluorite (It is used to make"sodium monofluorophosphate, which is added to some toothpastes.)
Fluorine is an element as it cannot be broken down into any simpler substances. Toothpaste is a mixture; Calcium fluoride is an ionic compound, made up of 1 Calcium atom for every 2 Fluoride atoms.
Write a chemical formula that represents both a molecule and a compound. Write a formula that represents a compound but not a molecule.
H2O; NaCl
Name Symbol hydride nitride phosphide oxide sulfide selenide fluoride chloride bromide iodide
H− N3− P3− O2− S2− Se2− F− Cl− Br− I −
Describe the crystal structures of cesium chloride and ammonium chloride. How are they similar, and how are they different? (Objective 33)
In cesium chloride, the cesium ions sit in the center of each cube, surrounded by eight chloride ions. Ammonium chloride has the same general structure as cesium chloride, with ammonium ions playing the same role in the NH4Cl structure as cesium ions play in CsCl. The key idea is that because of its overall positive charge, the polyatomic ammonium ion acts like the monatomic cesium ion, Cs+
An atom or group of atoms that has lost or gained one or more electrons to create a charged particle is called a(n) _____________________.
Ion
Would you expect the bonds between the following atoms to be ionic or covalent bonds? (Objective 8) a. Li-F b. C-N
Li-F is ionic; C-N is covalent
_____________ compounds are composed of _____________, which are collections of atoms held together by all covalent bonds.
Molecular...molecules of 2 or more nonmetals....
A(n) ______________________ is an uncharged collection of atoms held together with covalent bonds.
Molecule
How many valence electrons does each atom of the following elements have? (Objective 10) a. N b. S
N has 5 valence electrons and S has 6 valance electrons
How may protons and electrons do each of the following ions have? a. N3- b. Ba2+
N3- has 7 protons and 10 electrons; Ba2+ has 56 protons and 54 electrons.
What is wrong with using the name nitrogen oxide for NO? Why can't you be sure of the formula that corresponds to the name phosphorus chloride? (Objective 28)
NO may refer to a binary covalent compound of nitrogen and oxygen, aka Nitrogen oxide, or it may refer to a polyatomic ion, for example NO3. So for clarification it should be written with the appropriate prefixes. For example, as nitrogen monoxide. The name phosphorus chloride is ambiguous as written. The 2nd element requires a prefix for clarity. Otherwise we are uncertain of the ratio of phosphorus atoms to chloride atoms. For clarity if we are speaking of PCl it should be written as phosphorus monochloride for clarity.
The atom in a chemical bond that attracts electrons more strongly acquires a(n) _____________ charge, and the other atom acquires a(n) _____________ charge. If the electron transfer is significant but not enough to form ions, the atoms acquire _____________ and _____________ charges. The bond in this situation is called a polar covalent bond.
Negative...Positive.....Slightly negative...Slightly positive
When the difference in electron-attracting ability between atoms in a chemical bond is _____________, the atoms in the bond will have no significant partial charges. We call this type of bond a nonpolar covalent bond.
Neutral
The sum of the numbers of covalent bonds and lone pairs for the most common bonding patterns of the atoms of nitrogen, phosphorus, oxygen, sulfur, selenium, and the halogens is ____________.
Nitrogen 3 CB and 1 LP; Phosphorus 3 CB and 1 LP; Oxygen 2 CB and 2 LP; Sulfur 2 CB and 2 LP; Se 2 CB and 2 LP; the halogens 1 CB and 3 CB. Total is 24.
Because particles with opposite charges attract each other, there is an attraction between _____________ and _____________. This attraction is called an ionic bond.
Positive (protons) and Negative (Electrons)
Monatomic cations
Positively charged particles, such as Na+, Ca2+, and Al3+, that contain single atoms with a positive charge.
Atom H Hydr C Carb N Nitr P Phosph O Ox S Sulf Se Selen F Flour Cl Chlor Br Brom I Iod-
Root + ide Hydr Carb Nitr Phosph Ox Sulf Selen Flour Chlor Brom Iod-
Write the name for each of these monatomic ions. (Objective 30) a. Na+ b. Br- c. Al3+
Sodium Ion, Bromide Ion, Aluminum Ion
Compounds that have ionic bonds, such as the sodium chloride in table salt, are _____________ at room temperature and pressure, but compounds with all covalent bonds, such as hydrogen chloride and water, can be _____________ and _____________ as well as solids.
Solid.... Liquid...Gas
A space-filling model provides the most accurate representation of the _____________ for the atoms in CH4.
Space-filling models are useful because they show how much space an atom (or molecule) occupies
A chemical formula is a concise written description of the components of a chemical compound. It identifies the elements in the compound by their _____________ and indicates the relative number of atoms of each element with _____________.
Symbols...Subscripts
Bond angle
The angle formed by straight lines (representing bonds) connecting the nuclei of three adjacent atoms.
Ionic bond
The attraction between a cation and an anion.
Organic chemistry
The branch of chemistry that involves the study of carbon-based compounds.
Valence electrons
The electrons that are most important in the formation of chemical bonds. The number of valence electrons for the atoms of an element is equal to the element's A-group number on the periodic table. (A more comprehensive definition of valence electrons appears in Chapter 12.)
Tetrahedral
The molecular shape that keeps the negative charge of four electron groups as far apart as possible. This shape has angles of 109.5° between the atoms.
Describe the nuclear model of the atom.
The nuclear model. Atoms contain three sub-atomic particles called protons, neutrons and electrons. The protons and neutrons are found in the nucleus at the centre of the atom. The nucleus is very much smaller than the atom as a whole.
Describe the particle nature of solids, liquids, and gases. Your description should include the motion of the particles and the attractions between the particles.
The particles of solids are densely packed with great attraction towards each other. They do bump up against each other, but within a very constricted space. It is this great attraction and density that gives solids their shapes. The particles of liquids have more empty space between them, though there is still significant attraction between the colliding particles. The empty space between the particles allows for liquids to flow and for them to take on the shape of the vessel that holds them. The particles of gas have the most empty space between them, with very little attraction between particles. The particles move in a straight path, and when they do collide they change direction and velocity. It is the lack of attraction and the vast space between the particles that allows gases to expand and change volume easily.
Lone pair
Two electrons that are not involved in the covalent bonds between atoms but are important for explaining the arrangement of atoms in molecules. They are represented by pairs of dots in Lewis structures.
When a substance has a(n) _____________, must by definition be either an element or a compound, and it is considered a pure substance.
a constant composition—when it can be described by a chemical formula
Write the chemical formula for each of the following compounds. List the symbols for the elements in the order that the elements are mentioned in the description. a. a compound with molecules that consist of two phosphorus atoms and five oxygen atoms. b. a compound with molecules that consist of two hydrogen atoms and one sulfur atom. c. a compound that contains three calcium atoms for every two nitrogen atoms. d. a compound with molecules that consist of 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms.
a: P205; b: H2S; c: Ca3N2; d: C12H22O11
Ionic compounds whose formula contains one symbol for a metal and one symbol for a nonmetal are called ____________ ionic compounds.
binary ionic compound
Lewis structures are useful for showing how the atoms in a molecule are connected by covalent bonds, but they do not always give a clear description of how the atoms are _____________.
charged
There are relatively few chemical elements, but there are millions of chemical _____________.
compounds
Write the name for each of these polyatomic ions. (Objectives 34 & 35) a. OH- b. CO32- c. HCO3-
hydroxide, carbonate, hydrogen carbonate
It is common for hydrogen atoms to be transferred from one ion or molecule to another ion or molecule. When this happens, the hydrogen atom is usually transferred without its electron, as _____________.
it is common for hydrogen atoms to be transferred from one ion or molecule to another ion or molecule. When this happens, the hydrogen atom is usually transferred without its electron, as H+
Metallic atoms hold some of their electrons relatively loosely, and as a result, they tend to _____________ electrons and form cations. In contrast, nonmetallic atoms attract electrons more strongly than metallic atoms, so nonmetals tend to _____________ electrons and form anions.
lose electrons; gain electrons
The ions in ionic solids take the arrangement that provides the greatest _____________ while minimizing the _____________.
maximizing attraction....minimizing repulsions
The names of _____________ always start with the name of the metal, sometimes followed by a Roman numeral to indicate the charge of the ion.
monatomic cations
When atoms gain electrons and form anions,
negative; positive
Nonmetallic atoms form anions to get the same number of electrons as the nearest _____________.
noble gas
You can recognize binary covalent compounds from their formulas, which contain symbols for only two _____________ elements.
nonmetallic
The noble gases (group 8A) have a(n) _____________ of electrons (except for helium, which has only two electrons total), and they are so stable that they rarely form chemical bonds with other atoms.
octet
The actual shape of a molecule can be predicted by recognizing that the negatively charged electrons that form covalent bonds and lone pairs _____________ each other. Therefore, the most stable arrangement of the electron groups is the molecular shape that keeps the groups as far away from each other as possible.
repel each other
A compound is a substance that contains two or more elements, the atoms of those elements always combining in the same _____________.
substance that contains two or more elements, the atoms of these elements always combining in the same whole‑number ratio
Name: -H2O -NH3 -CH4 -C2H6 -C3H8
water , ammonia, methane, ethane, propane
To write the name that corresponds to a formula for a compound, you need to develop the ability to recognize the formula as representing a(n) ____________.
you need to develop the ability to recognize the formula as representing a specific type of compound.
