What is Chemistry?
Jan 18, 2016
What is Chemistry?
The study of the properties of matter and the changes
that matter undergoes.
What is the modern definition of the atom?
What is the modern definition of the atom?
The smallest representative particle of an element that has all of the properties of that element.
What is an element?
What is an element?A substance that cannot be
separated into simpler substances by chemical means. All atoms of an element are alike in properties and reactivities.
What is a molecule?
What is a molecule?
A molecule is formed when two or more atoms bond covalently.
What are the four states of matter in order of increasing energy?
What are the four states of matter in order of increasing energy?
solid→ liquid→gas→plasma
What is the Law of Constant Composition?
What is the Law of Constant Composition?
The elemental composition of a pure compound is always the same.
What is the difference between a chemical and physical change?
In a physical change the substance alters its appearance, but not its chemical composition.
Water becomes ice, but is still H2O
In a chemical change, the substance is transformed into a different substance.
All changes of state are what type of changes?
All changes of state are what type of changes?
Physical
All combustion reactions are what type of reaction?
ChemicalCombustion reactions always have O2 as a reactant.
What are the three subatomic particles that chemists are concerned with?
Protons, neutrons and electrons
What is the electrical charge of a proton or electron?
1.602 x 10-19C is the amount of charge per electron or proton.
Protons positiveElectrons are negative
For simplicity, what do we consider to be the charge on an electron or proton?
-1 electron+1 proton
How do the number of protons and electrons compare in an atom of an element?
They are equal.
Which subatomic particles are found in the nucleus of an atom?
Protons and neutrons
What makes up most of the volume of an atom?
The electron cloud
Atoms have extremely small masses (the heaviest atom is on the order of 4 x 10-22 g) We use the amu to describe the mass of atoms and molecules. What is the amu?
The atomic mass unit. The mass of a proton and neutron are both considered to be 1 amu. An electron is about 2000 times smaller than a proton and is considered to be 0 amu.
On what element was the amu based?
On what element was the amu based?
Carbon -12
Atoms are extremely small. Most have diameters on the order of 10-10 m. What unit is commonly used to express the diameter of atoms?
Picometers and the Angstrom (Å)
1 Å = 10-10 m1pm = 10-12 m
The diameter of a carbon atom is 1.54 Å, express this diameter in picometers.
1.54Å x (10-10m) x (1012pm)
1Å 1m
=154 pm
What are the four basic forces?
What are the four basic forces?
GravitationalElectromagneticStrong nuclear forceWeak nuclear force
Which subatomic particle determines the identity of the element?
Which subatomic particle determines the identity of the element?
The number of protons determines the element
Each atom of an element has the same number of protons.
What are isotopes?
What are isotopes?Atoms of a given element that have different numbers of neutrons.
What is the atomic number?
The number of protons
What is the mass number?
What is the mass number?
The total number of protons and neutrons in the atom
How do we identify isotopes
Mass number Symbol Atomic number
For example
12C6
What is a nuclide
What is a nuclideAn atom of a specific isotope
How protons, neutrons and electrons are in an atom of 197Au.
All atoms of Au have 79 protons.
It is an atom so there are 79 electrons
There are 197 – 79 =118 neutrons
How many protons, electrons and neutrons are in an atom of 138Ba?
How many protons, electrons and neutrons are in an atom of 138Ba?
Protons and electrons 56138 -56 = 82 neutrons
Magnesium has three isotopes with mass numbers 24,25,and 26. a.)write the complete chemical symbol for each of these three isotopes b.)How many neutrons are in a nuclide of each isotope?
24Mg 25Mg 26Mg12 12 12
b.) 12, 13, and 14
Give the complete chemical symbol for the nuclide that contains 82 protons, 82 electrons and 126 neutrons.
208 Pb82
How is the atomic mass unit currently defined?
1/12 the mass of a carbon 12 nuclide
How is the average atomic mass of an element determined?
It is a weighted average. The masses of the various isotopes and their relative abundances are used.
Atomic weight is also known as the average atomic mass. Atomic mass is listed on the periodic table.
Naturally occurring chlorine is 75.78% 35Cl, which has a mass of 34.969, and 24.22% 37Cl which has an atomic mass of 36.966 amu. Calculate the average atomic mass of chlorine.
(.7578)(34969amu) + (.2422)(36.966)
26.50 amu + 8.953 amu
= 35.45 amu
Three isotopes of silicon occur in nature: 28Si (92.23%) with a mass of 27.97693 amu ;29Si (4.68%) with a mass of 28.97649 ; 30Si (3.09%) with a mass of 29.97377 amu. Calculate the atomic weight of silicon.
(.9223)(27.97693 amu) +
(.0468)(28.97649 amu) +
(.0309)(29.97377 amu)
=28.09 amu
What is the Periodic Table?
What is the Periodic Table?It is a very important tool that chemists use to organize and remember chemical facts.
What is the Periodic Table?The elements are arranged in order of increasing atomic number. The elements with similar properties are found in the same vertical columns.
What do we call the vertical columns on the periodic table?
What do we call the vertical columns on the periodic table?
A group or family
Why are the elements within a family similar in properties and chemical reactivity?
Why are the elements within a family similar in properties and chemical reactivity?
They have the same number of valence electrons
What are the common names associated with the following groups?
Group 1- Alkali metalsGroup 2 –Alkaline earth
metalsGroups 3-12 - Transition
metals
Group 13- Boron family
Group 14- Carbon family
Group 15- Nitrogen family
Group 16- Oxygen family
Group 17- Halogens
Group 18- Noble gases
Where are the metals on the periodic table?
The metals are found to the left of the metalloids.
Most elements are metals.
Nonmetals?
Nonmetals are found to the right of the metalloids.
Metalloids?
The metalloids separate the metals and nonmetals.
All elements except Al and Po that border the zig zag line are metalloids.
What are characteristics of metals?
What are characteristics of metals?
High lusterGood conductors of heat
and electricityMalleableDuctileTend to lose electrons
What are characteristics of nonmetals?
DullPoor conductorsBrittleTend to gain electrons or to
bond covalently with other nonmetals
What is the only family of elements in which the atoms are found in nature as isolated atoms?
The noble gases
What is a molecule?
What is a molecule?
Two or more atoms bonded covalently.
Most molecular substances contain only nonmetals
What is a diatomic molecule?
What is a diatomic molecule?
A molecule composed of two atoms of the same type.
What are the 7 diatomic molecules?
What are the 7 diatomic molecules?
F2 Cl2 Br2 I2 H2 O2 N2
The halogens HON!
What is a molecular formula?
What is a molecular formula?
A chemical formula that indicates the actual number and types of atoms in a molecule.
What is an empirical formula?
Chemical formulas that give only the smallest whole number ratio of types of atoms.
What is the empirical formula for
a.)C6H12O6
b.) N2O
c.) B2H6
What is the empirical formula for
a.)C6H12O6 - CH2O
b.) N2O - N2O
c.) B2H6 - BH3
What are structural formulas?
What are structural formulas?
Structural formulas show which atoms are bonded to each other in the molecule.
What are some examples of structural formulas?
Lewis structuresPerspective drawingBall and stickSpace filling models
What is an ion?
What is an ion?When electrons are gained or lost from an atom, the atom becomes an ion.
What is a cation?
What is a cation?When electrons are lost the atom becomes a positively charged ion or a cation.
What is an anion?
What is an anion?When electrons are gained the atom becomes a negatively charged ion or an anion.
Which elements form cations?
The metals tend to form cations because they tend to lose electrons.
Which elements form anions?
The nonmetals tend to form anions because they tend to gain electrons.
How can you predict the charge that an ion will have?
How can you predict the charge that an ion will have?Look at the number of
valence electrons the atom has. Then determine the number of electrons that would need to be lost or gained to have a full valence shell.
What is a polyatomic ion?
What is a polyatomic ion?
An ion composed of more than one atom bonded together covalently. The entire group has a charge.
What is a monatomic ion?
An ion that originated from a single atom. “ A single atom ion”
Define an ionic compound.
Define an ionic compound.
A compound consisting of ions.
Ionic compounds are typically combinations of metals and nonmetals
What type of formula do we use to describe ionic compounds?
What type of formula do we use to describe ionic compounds?
The empirical formulaIonic compounds tend to
have large numbers of ions bonded together in the crystal lattice. The empirical formula gives the ratio of ions
What is the criss cross method?
What is the criss cross method?
A method used to determine the formula for ionic compounds. The charge for one ion becomes the subscript for the other.
How can you predict if a compound is ionic or covalent?
If the substance has a metal and a nonmetal it is probably ionic
If the substance has two nonmetals it is probably covalent.
Which of the following would you expect to be ionic?
N2O Na2O CaCl2
SF4 CBr4 FeS
P4O6 PbF2
Which of the following would you expect to be ionic?
N2O Na2O CaCl2
Covalent ionic ionic
SF4 CBr4 FeSCovalent covalent ionic
P4O6 PbF2
Covalent ionic
What is the formula for the following compounds?
Aluminum oxide
Magnesium nitrate
Zinc sulfate
Iron III Carbonate
Sodium phosphate
Iron II chloride
What is the formula for the following compounds?
Aluminum oxide – Al2O3
Magnesium nitrate – Mg(NO3)2
Zinc sulfate- ZnSO4
Iron III Carbonate- Fe2(CO3)3
Sodium phosphate- Na3PO4
Iron II chloride – FeCl2
Naming Inorganic ionic compounds
Name the cation first.* The cation is always named before the anion.*cations named from a metal have the same name as the metal ( Al+3 is an aluminum ion)
Naming Inorganic ionic compounds
* Ions formed from a single atom are called monatomic ions.
* If the ion can have more than one charge, a roman numeral must be used to indicate charge.
Naming Inorganic ionic compounds
For example:
Iron II – Fe+2
Iron III – Fe+3
Naming Inorganic ionic compounds
If the ion is formed from several atoms covalently bonded to each other, it is a polyatomic ion.
Ammonium – NH4+
Sulfate – SO4-2
Naming Inorganic ionic compounds
Name the anion
Monatomic ions are named by replacing the ending with –ide.
Hydrogen becomes hydride
Oxygen becomes oxide
How do you identify polyatomic ions with oxygen?They end in –ate for the most common form, and –ite for the anion that has the same charge but one less oxgen.
With respect to polyatomic ions, what do the following prefixes indicate?
Per- indicates one more oxygen than the oxyanion with the –ate ending.
Hypo- one less oxygen than the -ite oxyanion
With respect to polyatomic ions, what do the following prefixes indicate?
ClO4- perchlorate
ClO3- chlorate
ClO2- chlorite
ClO- - hypochlorite
How are anions derived by adding a H+ named?
How are anions derived by adding a H+ named?
By adding as a prefix the word hydrogen for one hydrogen or dihydrogen for two hydrogen atoms.
How are anions derived by adding a H+ named?
For every hydrogen that is added the negative charge on the anion is decreased by one.
examples
CO3-2 Carbonate
HCO3- hydrogen carbonate
PO4-3 Phosphate
H2PO4- dihydrogen Phosphate
The formula for selenate is SeO4
2-. Write the formula for the selenite ion.
The formula for selenate is SeO4
2-. Write the formula for the selenite ion.-ate is changed to -ite so one
less oxygen is present.SeO3
2-
The formula for the bromate ion is BrO3
-. Write the formula for the hypobromite ion.
The formula for the bromate ion is BrO3
-. Write the formula for the hypobromite ion.
BrO-
Name the following compoundsa.) K2SO4
b.) Ba(OH)2
c.) FeCl3
Name the following compounds
a.) K2SO4 –Potassium sulfate
b.) Ba(OH)2 – Barium hydroxide
c.) FeCl3 – Iron III chloride
Name the following compoundsa.) NH4Br
b.) Cr2O3
c.) Co(NO3)2
Name the following compounds
a.) NH4Br- Ammonium bromide
b.) Cr2O3 – Chromium III oxide
c.) Co(NO3)2 – cobalt II nitrate
Write the chemical formula for the following compounds
Potassium sulfide
Calcium hydrogen carbonate
Nickel II perchlorate
Write the chemical formula for the following compounds
Potassium sulfide
K2SCalcium hydrogen carbonate
Ca(HCO3)2
Nickel II perchlorate
Ni(ClO4)2
What is the name for the following compounds?
MgSO4
AgS
Pb(NO3)2
What is the name for the following compounds?
MgSO4 – Magnesium sulfate
Ag2S – silver sulfide
Pb(NO3)2- lead II nitrate
Define an acid.
Define an acid.
A substance that has hydrogen ions as the cation and that yields H+ ions when dissolved in water.
How do you name an acid formed from a monatomic anion?Change the –ide ending of the anion to –ic and add the prefix hydro.
For example
HClH2SHBrH3N
For example
HCl hydrochloric acidH2S hydrosulfic acid ( May also
be hydrosulfuric acid)
HBr hydrobromic acidH3N hydronitric acid
Exception to the rule:
When the cyanide ion is used the acid is named as if it were a monatomic ion.
HCN is hydrocyanic acid
How do you name acids formed from polyatomic ions that have the –ate ending?
How do you name acids formed from polyatomic ions that have the –ate ending?Use the name of the
polyatomic anion but change the –ate ending to –ic and add the word acid.
Name H2CO3
Name H2CO3 You know it is an acid b/c
the cation is hydrogen.Take the carbonate name
change -ate to -ic and add the word acid.
Carbonic acid
Name H3PO4 You know it is an acid b/c
the cation is hydrogen.Take the phosphate name
change -ate to -ic and add the word acid.
Phosphoric acid
Name H2SO4 You know it is an acid b/c
the cation is hydrogen.Take the sulfate name
change -ate to -ic and add the word acid.
Sulfuric acid
For all acids, the number of hydrogen atoms is determined by the charge on the anion.
How do you name acids formed from polyatomic ions that have the –ite ending?
How do you name acids formed from polyatomic ions that have the –ite ending?Change the –ite ending to –ous
and add the word acid.
HNO2 – nitrous acid
H3PO3 phosphorous acid
H2SO3 sulfurous acid
Name the following acidsHCN
HNO3
H2SO4
H2SO3
Name the following acidsHCN hydrocyanic acid
HNO3 nitric acid
H2SO4 sulfuric acid
H2SO3 sulfurous acid
Naming molecular compounds
1.) The name of the element furthest to the left on the periodic table is usually written first.
Naming molecular compounds
2.) If both elements are in the same group, the lower one is named first.
Naming molecular compounds
3.) The name of the second element is given the suffix -ide.
Naming molecular compounds
4. Greek prefixes are used to indicate the number of atoms for each element. If the first element has only one atom, then a prefix is not used.
What are the prefixes that are used to indicate the number of atoms?
1- mono 6- hexa
2- di 7- hepta
3- tri 8- octa
4- tetra 9 – nona
5- penta 10- deca
Name the following
SO2
PCl5
N2O3
Name the following
SO2 – Sulfur dioxide
PCl5 – phosphorus pentachloride
N2O3 - dinitrogen trioxide
Give the formula for the following
A.) silicon tetrabromide
B.) disulfur dichloride
Give the formula for the following
A.) silicon tetrabromide – SiBr4
B.) disulfur dichloride – S2Cl2
What are organic compounds?
What are organic compounds?
Compounds that contain mainly hydrogen and carbon and often oxygen, nitrogen or other elements.
What are organic compounds?
Glucose – C6H12O6
Propane – C3H8
What are hydrocarbons?
What are hydrocarbons?
Compounds that contain only hydrogen and carbon
for example :C4H10
butane
What are alkanes?
What are alkanes?
A hydrocarbon in which carbon is bonded to four other atoms and all bonds are single bonds.
What are alkenes?
What are alkenes?
A hydrocarbon in which carbon is bonded to other carbon atoms and one or more of the bonds for carbon is a double bond
What are alkynes?
What are alkynes?
A hydrocarbon in which carbon is bonded to other carbon atoms and one or more of the bonds for carbon is a triple bond
What are the prefixes that are used to indicate the number of carbon atoms?
1- meth 6- hexa2- eth 7- hepta3- prop 8- octa4- but 9- nona5- pent 10 - deca
when naming hydrocarbons…
Alkanes end in –anei.e.,Methane, propane, heptane
Alkenes end in –enei.e., ethene, butene
Alkynes end in –ynei.e., propyne, pentyne
Hydrocarbons that have all single bonds are called saturated . If the hydrocarbon has one or more multiple bonds it is unsaturated.
what is an alcohol?
An alcohol is formed when a hydrogen on an alkane is replaced by an –OH group ( an hydroxyl group)
How are alcohols named.
Use the name of the alkane the alcohol was derived from and change the ending to -ol
what is an alcohol?Methane becomes methanol
Ethane become ethanol
Butane become butanol
what is an alcohol?
The properties of the alcohol are very different than the alkane they were formed from.