Unit 3 and 4 Flashcards
What did John Dalton do?
- Determined atomic masses of elements
- Found how elements combine to form compounds
- Chemical formulas show characteristic proportions
The ratio of the two masses of one element that react with a given mass of another element to form two different compounds is the ratio of two small whole numbers
Law of multiple proportions
Composed of atoms held together in molecules by covalent bonds
Molecular compound
What are the building blocks of molecular compounds?
Molecules containing atoms of 2 Nonmetals
A bond between two atoms created by sharing one of more pairs of electrons
Covalent bond
Nonmetal oxides found in atmosphere
CO2, H2O, SO3, SO2, NO
A notation showing the number and type of atoms present in one molecule of a molecular compound
Molecular formula
A compound composed of positively and negatively charged ions held together by electrostatic attraction
Ionic compound
What two things form an ionic compound?
Metallic element and nonmetal
A positively charged particle created when an atom of molecule loses one or more electrons
Cation
A negatively charged particle created when an atom or molecule gains one of more electrons
Anion
A formula showing the smallest whole number ratio of elements in a compound
Empirical formula
The smallest electrically neutral unit of an ionic compound
Formula unit
Group 1 of periodic table
Lose 1 electron and form 1+ ions
Group 2 of periodic table
Lose 2 electrons and form 2+ ions
Group 13 of periodic table
Lose 3 electrons and form 3+ ions
As metallic elements lose electrons in forming ionic compounds, their nonmetallic partners (blank) so overall charge = zero
Gain them
Group 17 of periodic table
1-
Group 16 of periodic table
2-
Group 15 of periodic table
3-
Steps for molecular formula of a binary molecular compound to form a compound name
1) start with name of first element in formula
2) change ending of name of second element to -ide
3) add prefixes to indicate # of atoms
Prefix for naming compounds and writing formulas: 1
mono
Prefix for naming compounds and writing formulas: 2
Di
Prefix for naming compounds and writing formulas: 3
Tri
Prefix for naming compounds and writing formulas: 4
Tetra
Prefix for naming compounds and writing formulas: 5
Penta
Prefix for naming compounds and writing formulas: 6
Hexa
Prefix for naming compounds and writing formulas: 7
Hepta
Prefix for naming compounds and writing formulas: 8
Octa
Prefix for naming compounds and writing formulas: 9
Nona
Prefix for naming compounds and writing formulas: 10
Deca
Prefix for naming compounds and writing formulas: 11
Undeca
Prefix for naming compounds and writing formulas: 12
Dodeca
A pure substance composed of two or more elements
Compound
Types of compounds
Ionic and molecular
Consist of ions
Ionic compounds
Consist of molecules
Molecular compounds
Smallest unit of a molecular compound that retains the characteristic of that compound
Molecule
Indicates the # of atoms of each type within a molecule
Molecular formula
Sticks in ball and stick model
Covalent bonds
What hold the balls together in a molecule
Covalent bonds
A molecular formula that shows structural information and/or groups of atoms
Condensed formula
Representation of how atoms are attached within a molecule
Structural formula
Charged groups of two or more atoms joined together by covalent bonds
Polyatomic ions
Polyatomic ions that contain oxygen in combination with one or more other elements
Oxoanions
Compounds that highlight particular chemical properties
Acids
What release hydrogen ions when they dissolve in water?
Acids
Steps to name binary acids
1) add prefix hydro to name of element and replace last syllable with ic + acid
Mass of one molecule of a molecular compound
Molecular mass
The mass of one formula unit of an ionic compound
Formula mass
Hold together atoms within a molecule
Intramolecular forces
Forces between neighboring molecules
Intermolecular forces
Used to provide profiles of structures rather than images of single molecules
Atomic force microscopy
How do we determine the mass (in grams per mole) of a molecule like ethanol or water?
Molecular weight
Sum of atomic weights of all atoms in a molecule
Molecular weight
What is another term for molecular weight?
Molar mass
Atoms or groups of atoms with a positive or negative charge
Ions
Form when atoms lose one or more electrons
Cations
Form when an atom gains one or more electrons
Anions
What are the general rules for predicting ion charges?
- metals lose electrons to form cations
- Nonmetals gain electrons to form anions
By losing or gaining electrons, atoms have the same # of electrons as the nearest group (blank) atom
8A atom
1A ion charge
+1
2A ion charge
+2
3A ion charge
+3
4A ion charge
-4
5A ion charge
-3
6A ion charge
-2
7A ion charge
-1
Transition metals charges
Widely variable
An ion consisting of more than one atom
Polyatomic ions
Steps for naming a binary ionic compound
1) start with name of cation
2) add name of anion (name of element with ending ide)
No prefixes
Electrically neutral
Name SrCl2
Strontium chloride
Name NaF
Sodium fluoride
Name MgO
Magnesium oxide
Name CaBr2
Calcium bromide
Write the formulae for aluminum oxide
Al2O3
Charges switch when forming subscripts
Techniques for the separation of mixtures
Chromatography
Formulas of ionic compounds- ionic compounds should have (blank) net charge
No
Sum of + and - = 0
Steps for naming ionic compounds
1) name the positive ion first (cation) followed by the negative ion (anion)
What are the negative ions?
H- C4- N3- O2- F- P3- S2- Cl- Se2- Br- Te2- I-
Fe2+
Iron (II) ion
Ferron
Fe3+
Iron (III) ion
Ferric
Name CaF2
Calcium fluoride
Name Mg(NO3)2
Magnesium nitrate
Name Fe3(PO4)2
Iron (II) phosphate
KBr
Potassium bromide
Li2CO3
Lithium carbonate
Coulombs law in words
Cations and anions are attracted to each other by electrostatic forces
As ion charge increases, the attractive force (blank)
Increases
As the distance between the ions increases, the attractive force (blank)
Decreases
Properties of ionic compounds
- exist as 3D arrays of anions and cations
- cations surrounded by anions and vice versa
- tend to be transparent, hard, and brittle as crystalline solids
Bonding =
Electron sharing
Molecular compounds formed between
2 nonmetals
Rules for naming molecular compounds
1) first element in formula is named first, using full element name
2) name the second element as if it were an anion (ide)
3) prefixed are used to denote the number of atoms present
4) prefix mono never used for first element
Name NI3
Nitrogen triiodide
SF6
Sulfur hexafluroride
P4O10
Tetraphosphorus decoxide
02F2
Dio y gen difluoride
The composition of a compound expressed in terms of the percentage by mass of each element in the compound
Percent composition
% composition equation
Mass of element / molar mass x 100
Mass in grams of 1 mole of a compound
Molar mass
How to find the mass percent of an element:
Mass of element / total mass of the compound
Formula determined from percent composition
Empirical formula
Steps to find the empirical formula from % composition
1) assume 100 g of substance, % values = mass values, add % to 100
2) convert mass to moles
3) compute mole ratio by reducing one of the mole values to 1
4) convert ratio into whole #s if necessary
Represent the relative proportions of the ions in the formula unit of an ionic compound
Empirical formulas
The key to translating empirical formulas into molecular formulas is to determine the (blank) and the key to determining this is knowing the (blank)
Value of n
Molecular mass
Who came up with the mass spectrometer?
Francis Aston
An instrument that separates and counts ions according to their mass
Mass spectrometer
A graph of the data from a mass spectrometer, where m/z ratios of the deflected particles are plotted against the # of particles with a particular mass
Mass spectrum
The peak of the highest mass in a mass spectrum; it has the same mass as the molecule from which it came
Molecular ion (M+)
Simplest whole number ratio of elements in a compound
Empirical formula
How do you determine the molecular formula?
Obtain the molar mass of the compound experimentally (mass spectrometer)
What are the 3 steps to get a molecular formula?
1) get exp data
2) determine the mass of the empirical formula
3) find the ratio of the mass
Ionic compounds having water molecules trapped in their lattice
Hydrated compounds
Compounds without water (may be obtained by heating)
Anhydrous compounds
The quantitive relation between reactants and products in a chemical reaction
Stoichiometry
The sum of the masses of the reactants in a chemical reaction is equal to the sum of the masses of the products
Law of conservation of mass
A class of organic compounds composed of only hydrogen and carbon
Hydrocarbons
A heat-producing reaction between oxygen and another element or compound
Combustion reaction
What are the only products when the combustion of a hydrocarbon is complete?
Carbon dioxide and water
What are key reactions in the carbon cycle?
Photosynthesis and respiration
What two things do we need to know to determine mass of any substance involved in any chemical reaction?
1) mass of another substance in reaction
2) stoichiometric relation between 2 substances
Chemical equations indicate
The kind of reactants and produces
Relative amounts of reactants and products
The relationship between the amount of chemical reactants and products
Stoichiometry
The numbers in front of reactants and products
Stoichiometric coefficients
S, g, l, aq represent
Physical states of reactants and products
Matter can neither be created nor destroyed
Law of conservation of matter
The burning of organic compounds (fuel) in oxygen with the evolution of heat, CO2, and H2O
Combustion reaction
Steps to balance combustion reactions
1) write out correct formulas for reactants and products
2) balance C atoms
3) balance H atoms
4) balance O atoms
5) check work
The study of the quantitative aspects of chemical reactions
Stoichiometry
Stoichiometry problems should be attempted only when you have a (blank) chemical equation
Balanced
Maximum quantity of product that can be produced in a reaction
Theoretical yield
General plan for stoichiometry calculations
Mass reactant- moles reactant- stoichiometric factor- moles product- mass product
Percent yield
(Actual yield / theoretical yield)x100
A reactant that is consumed completely in a chemical reaction
Limiting reactant
The maximum amount of product possible in a chemical reaction for given quantities of reactants
Theoretical yield
The amount of product obtained from a chemical reaction, which is often less than the theoretical yield
Actual yield
The ration, expressed as a %, of the actual yield of a chemical reaction to the theoretical yield
Percent yield
The reagent in short supply (blank) the quantity of product that can be formed
Limits
Limiting reagent =
Limiting reactant
What are the two types of limiting reagent problems?
1) 1:1 ratio of reactants
2) non 1:1 ratios of reactants
Limiting reagent dictates (blank)
Theoretical yield
A laboratory procedure for determining the composition of a substance by burning it completely in oxygen to produce known compounds whose masses are used to determine the composition of the original material
Combustion analysis
Combustion analysis yield the percentages by mass of all atoms in a sample except (blank)
Oxygen
