Gen Chem Exam 2 Flashcards
How many grams are in 1 kg?
1000 grams
How many cm are in 1 m?
100 cm
How many mL are in 1 L?
1000 mL
Are numbers that are not 0 considered significant?
Yes
Is the number at the beginning of a decimal considered significant?
No
Is the zero between nonzero digits considered significant?
Yes
Is the zero at the end of a decimal considered significant?
Yes
Are the zeros in large numbers that are used as a placeholder considered significant?
No
Are the numbers written out in standard notation considered significant?
Yes
How many sig figs are in 122.45?
5
How many sig figs are in 205?
3
How many sig figs are in 16.00?
4
How many sig figs are in 5.70 x 10^3?
3
How many sig figs are in 0.075?
2
How many sig figs are in 850,000?
2
What are exact numbers?
Numbers that are not measured and are obtained by counting.
What are exact numbers used for?
In definitions to compare two units
- same measuring system
Rounding a number ___ the level of precision.
Decreases
How do you determine the amount of sig figs when multiplying/dividing?
Use the lowest number of sig figs of a number in the equation.
6.0 x 2.00 =
12 (2 sig figs)
How do you determine the amount of sig figs when adding/subtracting?
Use the same number of decimal places as the number with the fewest decimal places.
65.09 - 3.0 =
62.1 (1 decimal place)
What are the most commonly used prefixes for displaying LARGER numbers?
- Kilo
- Mega
- Giga
What are the most commonly used prefixes for displaying SMALLER numbers?
- Centi
- Milli
- Micro
- Nano
Cubic Centimeter (cc)
The volume of a cube whose dimensions are 1 cm on each side.
The cubic centimeter has the same volume as a ___.
Millimeter
Equalities
Use two different units to describe the same measured amount.
Can any equality be written as a conversion factor?
Yes
How many centimeters are in 1 inch?
2.54 cm
Density
Compares the mass of an object to its volume.
What is the formula for density?
mass/volume
Volume
The amount of space a substance occupies.
Mass
A measure of the quantity of material an object contains.
What are metric units used for measuring?
- Length
- Mass
- Volume
- Temperature
- Time
(everything basically)
Chemical Bonds
Formed when atoms gain, lose, or share valence electrons to acquire 8 valence electrons.
Noble Gas Configuration
8 valence electrons
Octet Rule
Atoms lose/gain electrons to have 8 valence electrons?
Ionic Bonds
Metals lose valence electrons and are transferred to a nonmetal.
Ionic Bonds turn into…
Ionic Compounds
Covalent Bonds
Nonmetals share electrons to attain a noble gas configuration.
Covalent Bonds turn into…
Molecular Compounds
Cations
Positively charged ions created by the loss of electrons
Anions
Negatively charged ions created by the gain of electrons.
Positive Ions
Metals lose electrons
Negative Ions
Nonmetals gain electrons
Ionic Compounds
Positive and negative charges held together by the strong electrical attractions between oppositely charged ions.
What are the 2 properties of ionic compounds?
- High melting points
- Solids at room temperature
Chemical Formula
Symbols and subscripts written in the lowest whole-number ration of the atoms/ions.
Formula Unit
The lowest whole number combination for the compound.
What does the sum of ion charges in a chemical formula equal?
0
How do you name an ionic compound?
- Write the full name of the metal
- Write the first syllable of the non metal
- Add “-ide” to the end of the non metal.
What can be placed after the name of an ion to reveal it’s charge?
Roman numeral
How do you find the ion charges in groups 1A and 2A?
Add a positive after the group number.
How do you find the ion charges in groups 5A, 6A, and 7A?
- 8 - (group number)
- Add a negative after
Name the ionic compound.
SnO2
Tin (IV) Oxide
What are the steps to writing formulas for compounds containing polyatomic ions?
- Identify cation and polyatomic ion (anion)
- Balance the charges using the criss cross method.
- Write the formula using the cation first, as well as their subscripts
How do you name ionic compounds with polyatomic ions?
- Write the name of the polyatomic ion (metal).
- Write the name of the polyatomic ion.
What is the simplest molecule?
H2
What type of bond is H2?
Covalent bond
Double Bond
Atoms share two pairs of electrons.
Triple Bond
Atoms share three pairs of electrons.
When do double and triple bonds form?
When there are not enough electrons to complete the octet.
What are the 3 exceptions to the octet rule?
- Hydrogen requires only 2 electrons to form a noble gas arrangement.
- Boron requires 6 electrons, which only makes 3 bonds.
- Beryllium requires 4 electrons, which only makes 2 bonds.
Electronegativity (EN)
An atoms ability to attract the shared electrons in a bond.
What does the higher value of electronegativity mean?
A greater ability to attract electrons.
Is there a scale of electronegativity?
There is a relative scale with no units.
What are the periodic trends of electronegativity?
- Increases from left to right
-Increases from top to bottom
-High for nonmetals
-Low for metals
How do you predict the polarity of a bond?
The difference in electronegativity of bonding atoms.
Nonpolar Bond
Electrons are shared equally
Polar Bond
Electrons are shared unequally
What is the EN value range for nonpolar covalent bonds?
0-0.4
What is the EN value range for polar covalent bonds?
0.5-1.8
What is the EN value range for ionic bonds?
1.9 +
Dipole
Seperation of charges in a polar bond.
What symbol is used to distinguish the dipole charges?
g (delta)
Which element has a + g and which one has a -g?
- Larger EN element has the -g
-Smaller EN element has the +g
What type of elements do ionic bonds form between?
metal and nonmetal ions
What does it mean when a molecule is blue on one end and red on the other?
The molecule is polar
What does it mean when a molecule is all green?
The molecule is non-polar
In what two situations do non-polar molecules arise?
- The molecule contains all non polar bonds (H2, Cl2, or CH4) and no lone pairs on the central atom.
- The molecule contains polar bonds, but the polar bonds cancel in a symmetrical arrangement.
What are the three non polar molecules?
- H2
- Cl2
- CH4
Why are polar molecules polar?
- The electrons are shared unequally
AND/OR - The polar bonds in the molecule do not cancel each other
Do single dipoles cancel?
No
In gases, molecules are ___ from each other.
Far
In liquids and solids, the molecules are ___ to each other.
close
Ion Dipole Interactions
Relatively strong electrostatic attractions between ions and polar molecules
-cause the dissolution of ionic solids in polar solvents such as water.
Dipole Dipole Interactions
Attractive forces between polar molecules.
Hydrogen Bond
Hydrogen bonded to F, O or N.
- VERY STRONG bond
- Type of dipole dipole interaction
Dispersion Forces
Weak attractions that can occur between two molecules.
What causes dispersion forces?
Temporary dipoles that develop when molecules bump into each other.
What do dispersion forces make possible?
Non polar molecules to form liquids and solids.
What types of molecules have dispersion forces?
ALL MOLECULES
What type of force is stronger: Intramolecular or Intermolecular?
INTRAmolecular
What types of bonds are INTRAmolecular bonds?
- Ionic Bond
- Covalent Bond
What types of bonds are INTERmolecular bonds?
- Hydrogen Bond
- Dipole-Dipole Interaction
- Dispersion Forces
What is an example of a dispersion force?
O2, F2, etc.
What is an example of hydrogen bonding?
H2O
What is an example of Dipole-Dipole Attractions?
CH2O
Strong forces have a ___ melting/boiling point.
Higher
Chemical Change
A substance is converted
into one or more substances with different
formulas and different properties.
What are the 4 possible observations of a chemical change?
- Formation of bubbles
- Color change
- Production of a solid
- Heat produced or absorbed
What size of a chemical equation do reactants go on?
Left
What side of a chemical equation do products go on?
Right
What two factors help identify a balanced equation?
- No atoms are lost or created
- The number of atoms on the reactant side is equal to the number of atoms of the same element on the product side.
Law of Conservation of Matter
- Matter cannot be created or destroyed
- No change in total mass occurs
- The mass of products is equal to the mass of reactants
Avogadros Number
6.02 x 10^23 items
The mole is a ___ term.
counting
1 mole contains ____ worth of items.
avogadro’s number
What do the subscripts in a formula represent?
- The relationship of atoms in the formula.
- The moles of each element in 1 mole of compound.
How many moles of each element are in C9 H8 O4?
- C= 9 moles
- H = 8 moles
- O = 4 moles
What is the molar mass of an element used to convert?
- moles of an element to grams
- grams of an element to moles
How do you convert from grams of an element/compound to moles?
Using the molar mass (g/mole)
How do you convert from atoms to moles of an element?
Avogadros number
How do you convert from moles of an element to moles of a compound?
Formula Subscripts
How do you convert from molecules to moles of a compound?
Avogadros number
What are the 5 types of chemical reactions?
- Combination (synthesis)
- Decomposition
- Single Replacement
- Double Replacement
- Combustion
Can chemical reactions fit into more than one type of reaction?
Yes
Combination (Synthesis) Reaction
- Two or more elements form one product
- Simple compounds combine to form one product
Decomposition Reaction
One substance splits into two or more simpler substances
Single Replacement Reaction
One element takes the place of a different element in another reacting compound
Double Replacement Reaction
Both ions in the reactant compounds switch places.
Combustion Reaction
- A carbon-hydrogen containing compound burns in oxygen gas to form CO2 and H2O
- Energy is released as a product in the form of heat.
What type of chemical reaction is…
2Mg + O2 –> 2MgO
Combination (synthesis)
What type of chemical reaction is…
2HgO –> 2 Hg + O2
Decomposition
What type of chemical reaction is…
Zn + 2HCl –> ZnCl2
Single Replacement
What type of chemical reaction is…
AgNO3 + NaCl –> AgCl + NaNO3
Double Replacement
What type of chemical reaction is…
CH4 + 2O2 –> CO2 + 2H2O + energy
Combustion
How is carbon monoxide (CO) produced?
When oxygen supply is limited, an incomplete combustion from burning gas, oil or wood occurs
Why is CO toxic?
It binds to the hemoglobin in your blood and blocks oxygen from binding.
What is needed when burning fuels?
Good ventilation
What is happening to electrons when rust forms?
The electrons are transferring from one substance to another.
Oxidation Reduction Reactions
Electrons are transferred from one substance to another.
What can oxidation not occur without?
Reduction
“OIL RIG”
Oxidation
Is
Loss of electrons
Reduction
Is
Gain of electrons
What type of reaction is this…
Cu –> Cu2+ + 2e
Oxidation Reduction
