Introduction to chemistry

Question 1

Definition of Matter

Answer 1

anything with mass and occupies space

Question 2

Definition of Mass

Answer 2

an actual measurement of matter present (total amount of matter in an object)

Question 3

Definition of Weight

Answer 3

force of gravity on an object

Question 4

What are the differences between physical and chemical properties?

Answer 4

• Physical properties = unchanged of matter’s composition (texture, smell, shape, color
• Chemical properties = changed into other matter (burning paper, burning glass)

Question 5

What are the differences between physical and chemical changes?

Answer 5

• Physical changes = unchanged substance composition and identities– change appearance (melting, changing shape, sublimation of solids to gases, liquid evaporation to form gases)
• Chemical changes = matters changing with 1+ new substance of new properties.

Question 6

Is limestone heated, producing lime and carbon dioxide, a physical or chemical change?

Answer 6

chemical

Question 7

Is Antacid seltzer dissolved in water a physical or chemical change?

Answer 7

chemical

Question 8

Is milk souring a physical or chemical change?

Answer 8

chemical (change in taste and odor indicate new substance)

Question 9

Is dynamite stick exploding a physical or chemical change?

Answer 9

chemical (gases and smoke released indicate new substance)

Question 10

Is water boiling a physical or chemical change?

Answer 10

physical

Question 11

Is dissolving salt in water a physical or chemical change?

Answer 11

physical (as change in state is a physical change)

Question 12

Is shiny metal aluminum reacting with orange, liquid bromine a physical or chemical change?

Answer 12

chemical

Question 13

Is dissolving salt in water a physical or chemical change?

Answer 13

physical (as change in state is a physical change)

Question 14

Is cup of household bleach changing shirt color a physical or chemical change?

Answer 14

chemical

Question 15

Is water vapor from an exhaled breath condenses in the air in cold a physical or chemical change?

Answer 15

physical

Question 16

Acetylsalicylic acid/aspirin is a white solid melting at 136 degrees C. If heated gently, a gas is given off. After the gas stops, a white solid remains melts at a temperature different from 136 degrees C.

Have the aspirin molecules been changed by the process? Explain your answer.

Answer 16

Yes. The change in melting point shows another substance is formed. The evolved gas is also a different substance.

Question 17

What are the differences between pure substances and mixtures?

Answer 17

• Pure substances are constant compositions and fixed sets of physical and chemical properties (pure water always has the same proportion of H and O and freezes at a specific temperature.)
• Mixtures vary in composition and are different for different compositions (a glass of sugar water can have crystals of sugar or many spoonfuls and sweetness and freezing points would carry.)

Question 18

What are the differences between homogeneous and heterogeneous mixtures/matter?

Answer 18

• Homogeneous mixtures have uniform appearances and same properties (sugar water).
• Heterogeneous mixtures have non-uniform properties and apperances (rock salt mixture and sand spready on snowy roads).

Question 19

What is a solution?

Answer 19

A homogeneous mixture of 2+ pure substances–either liquid mixture or solutions of gases and solids (like the air around)

Question 20

Is blood a homogeneous or heterogeneous mixture?

Answer 20

heterogeneous

Question 21

A pure substance is heated, cooled, put under pressure, and exposed to light but doesn’t change into anything. What can be said about classifying it as an element or compound? 

Answer 21

It can’t be classified as an element or compound regardless none of the tests changed it into a simpler substance, all possible tests were not done on it. Some tests may change it. 

Question 22

Mega- 

Answer 22

1,000,000 x basic unit (10⁶)

Question 23

Kilo-

Answer 23

1000 x basic unit (10³)

Question 24

What are the temperature conversion formulas? <br></br><ul><li>Celsius to farenheight</li><li>Farenheight to celsius</li><li>Celsius to Kelvin</li><li>Kelvin to Celsius</li></ul>

Answer 24

<ul><li>F^o = 9/5(C) + 32<span>^&nbsp;&nbsp;</span></li><li>C^o&nbsp;= 5/9(F - 32)<br></br></li><li>K = C + 273</li><li>C = K - 273</li></ul>

Question 25

Deci-

Answer 25

1/10 x basic unit (10^-1)

Question 26

Centi-

Answer 26

1/100 x basic unit (10^-2)

Question 27

Milli-

Answer 27

1/1000 x basic unit (10^-3)

Question 28

Micro-

Answer 28

1/1,000,000 x basic unit (10^-6)

Question 29

Nano-

Answer 29

1/1,000,000,000 x basic unit (10^-9)

Question 30

Acronym for measurement units

Answer 30

King Henry Died Unusually Drinking Chocolate Milk

• Kilo (1000 or 103)
• Hecto (100 or 102)
• Deca (10 or 101)
• Unit (1 unit)
• Deci (1/10 or 10-1)
• Centi (1/100 or 10-2)
• Milli (1/1000 or 10-3)

Question 31

What’s the temperature conversion formulas of Celsius to farenheight?

Answer 31

Fo = 9/5(C) + 32

Question 32

What’s the temperature conversion formulas of farenheight to Celsius?

Answer 32

Co = 5/9(F - 32)

Question 33

What’s the temperature conversion formulas of Celsius to Kelvin?

Answer 33

K = C + 273

Question 34

What’s the temperature conversion formulas of Kelvin to Celsius?

Answer 34

C = K - 273

Question 35

Remember: A Celsius degree is the same size of the Kelvin scale, but the scales have different zero points. <br></br>Both a degree in Celsius and a kelvin are<b> 9/5 </b>the size of a Farenheit degree’s size.

Answer 35

<img></img>

Question 36

What are the conversions for 1 cal to Joules and from 1kcal to Joules?

Answer 36

• 1 cal = 4.184 J
• 1kcal = 4184 J

Question 37

How to multiply numbers with exponents, divide numbers with exponents, raise to the power (multiple exponents), and raise to the zero power?

Answer 37

A number to the zero power is always 1.

Question 38

What are the rules for determining significant figures? 

Answer 38

<div><ul><li>Zeros not preceded by nonzero numbers are not
significant figures. These zeros are sometimes called leading zeros. </li><li>Zeros located between nonzero numbers are
significant figures. These zeros are sometimes called buried or confined zeros.</li><li>Zeros located at the end of a number are
significant figures if there is a decimal point present in the number. These
zeros are sometimes called trailing zeros. If not decimal point is present,
trailing zeros are not significant.&nbsp;</li></ul></div>

Question 39

What are the rules for calculating significant figures?

Answer 39

• The answer obtained by multiplication or
  division must contain the same number of significant figures as the quantity
  with the fewest significant figures used in the calculation
• The answer obtained by addition or subtraction
  must contain the same number of places to the right of the decimal as the
  quantity in the calculation with the fewest number of places to the right of
  the decimal.

Question 40

What are the formulas for density?

Answer 40

Density = Mass/Volume <br></br>Mass = Density*Volume<br></br>Volume = Mass/Density 

Question 41

What are isotope?

Answer 41

Isotopes are atoms that have the same atomic number but different mass numbers - that is, they are atoms of the same element that contain different numbers of neutrons in their nuclei <br></br><br></br><img></img><br></br><br></br>The top number is the mass number and the bottom is the atomic number. Also, remember that you can use the elemental name followed by the mass number (e.g., hydrogen-1, hydrogen-2, and hydrogen-3)

Question 42

Molar Mass - what is it? How do we find the molar mass? What is the molar mass in a concentrated solution? 

Answer 42

<div><b>Molar Mass</b>: The mass of one mole of a
substance (expressed in grams) is numerically equal to the substance’s atomic
or molecular mass (expressed in amu). For example, the molar mass of Carbon-12
is exactly 12 grams per mole, and the molar mass of water (H₂O) is ~
18 grams per mole (since the molecular weight of H₂O is ~ 18 amu. </div>

<div><br></br></div>

<div>Ex: Molar Mass of Sulfur (32.06 grams/1 mole) or (1
mole/32.06 grams)</div>

<div><br></br></div>

<div>Ex: Concentration of solution: 0.55 molar sodium
chloride solution = 0.55 M NaCl (0.55 mole NaCl/1 L solution) or (1 L
solution/0.55 mole NaCL)</div>

Question 43

What is Avogadro’s number?

Answer 43

6.022 x 10²³

Question 44

How many electrons can fit into the different subshells (s, p, d, f)

Answer 44

<div>S-subshell: has 1 orbital -- can fit 2 electrons</div>

<div>P-subshell: has 3 orbitals -- can fit 6
electrons</div>

<div>D-subshell: has 5 orbitals -- can fit 10
electrons</div>

<div>F-subshell: has 7 orbitals -- can fit 14
electrons</div>

Question 45

How many electrons can be in an orbital?

Answer 45

Only 2 electrons can fit in each orbital. For example, a 4p orbital can only have 2 electrons. 

Question 46

Different between a shell, subshell, and orbital

Answer 46

<img></img>

Question 47

What is Hund’s rule? 

Answer 47

<div>Hund's rule states that electrons will not join other
electrons in an orbital if an empty orbital of the same energy is available for
occupancy</div>

Question 48

What is the Pauli exclusion principle? 

Answer 48

Pauli exclusion
principle<b> </b>states that only electrons spinning in opposite
directions can simultaneously occupy the same orbital 

Question 49

Which subshells are filled in noble gasses? 

Answer 49

<div>Noble gas configurations<b> </b>– an electronic
configuration in which the last eight electrons occupy and fill the s and p
subshells (the shell is full) of the highest-occupied shell</div>

Question 50

Which are the s, p, d, and f blocks on a periodic table?

Answer 50

<img></img>

Question 51

What is a distinguishing electron?

Answer 51

<div>Distinguishing Electron<b> </b>is the last and
highest-energy electron found in an element&nbsp;</div>

Question 52

What are the classifications on a periodic table? 

Answer 52

<img></img>  <img></img><br></br><div><ul><li><b>Noble gases</b> make up the group found on
the extreme right of the periodic table – they are all gases at room
temperature and are unreactive with most other substances </li><li><b>Representative elements </b>are those in
which the distinguishing electron is found in an s or a p subshell</li><li><b>Transition elements </b>are those in which
the distinguishing electron is found in the d subshell</li><li><b>Inner-transition elements </b>are those in
which the distinguishing electron is found in the f subshell</li></ul><div><div>Elements can also be classified into metals,
nonmetals, and metalloids</div></div></div>

Question 53

What are the property differences between metals, non-metals, and metalloids? 

Answer 53

<div><b>Metals </b>– have the following properties</div>

<div><ul><li>High thermal conductivity – they transmit heat
readily </li><li>High electrical conductivity – they transmit
electricity readily </li><li>Ductility – they can be drawn into wires</li><li>Malleability – they can be hammered into thin
sheets</li><li>Luster – they have a characteristic “metallic”
appearance </li></ul></div>

<div><b>Nonmetals </b>– generally have chemical and
physical properties opposite to those of metals – under normal conditions, they
often occur as brittle, powdery solids or as gases</div>

<div><b><br></br></b></div>

<div><b>Metalloids </b>– such as boron and silicon,
have properties somewhat between those of metals and nonmetals, and they often
exhibit some of the characteristic properties of each type</div>

Question 54

Which elements on the periodic table are more metallic? 

Answer 54

<div>Elements get more metal as you move to the left
and down</div>

Question 55

What are the different property trends of a periodic table? 

Answer 55

<div><img></img><b><br></br></b></div>

<ul><li><b>Size of elements</b>: The sizes tend to increase from top to bottom of
each group, and then decreases from left to right for each period</li><li><b>Ionization energy</b>: (Opposite of size) Increases as we move to the right and decreases as we move down</li><li><b>Metallic</b>: Elements become less metallic as we move from left to right, and more metallic as we move from top to bottom (so most metallic are in bottom left)&nbsp;</li></ul>

Question 56

What is ionization energy? 

Answer 56

<div>Ionization energy is the energy required to remove an outermost
electron from an atom of the element in the gaseous state&nbsp;</div>

Question 57

What is the octet rule?

Answer 57

<div><img></img><b><br></br></b></div>

<div><br></br></div>

<div><b>Octet rule </b>refers to the tendency of
atoms to prefer to have eight electrons in the valence shell -- it is also a rule for predicting
behavior in reacting atoms – it says that atoms will gain or lose sufficient
energy electrons to achieve an outer electron arrangement identical to that of
a noble gas – 8 electrons</div>

Question 58

What are Lewis Structures?

Answer 58

<div><b>Lewis Structures </b>– representation of an
atom or ion in which the elemental symbol represents the atomic nucleus and all
but the valence-shell electrons – the valence-shell electrons are represented
by dots arranged around the elemental symbol&nbsp;</div>

<div><br></br></div>

<div><div>You can do this by writing out the electron
configuration or the simpler alternative for representative elements is to
refer to the periodic table and note that the number of valence-shell electrons
in the atoms of an element is the same number as the group in the periodic
table&nbsp;</div></div>

Question 59

Explain simple ions and ionic bond

Answer 59

<div><ul><li>S<b>imple ions </b>–
an atom that has acquired a net positive or negative charge by losing or
gaining electrons </li><li>And the attractive force between oppositely
charged atoms constitutes an&nbsp;<b>ionic bond </b>– the attractive forces that
holds togethers ions of opposite charge </li><li>As a general rule, metals lose electrons and
nonmetals gain electrons during ionic bond formation </li><li>The number of electrons lost or gained by a
single atom rarely exceeds three</li></ul></div>

Question 60

What is an ionic compound?

Answer 60

<ul><li><b>Ionic compounds --&nbsp;</b>chemical compound
composed of ions held together by electrostatic forces termed ionic bonding –
no atom can lose electrons unless another atom is available to accept them (e.g., FeCl₂)</li><li>Always
write metal first and non-metal second and just add -ide to the nonmetal</li><li>Never
need to write out the charges (just write Calcium Chloride), but you need to name the
charge with an inner transition metal, such as Iron (II) Chloride – FeCl₂
-- because you need to specify the charge</li><li>The ratio is determined by the charges on the
ions, which are determined by the number of electrons transferred&nbsp;<br></br></li></ul>

Question 61

What is a covalent bond?

Answer 61

<div>A chemical bond formed by sharing a pair of
electrons is a <b>covalent bond </b>– the attractive force that results between
two atoms that are both attracted to a shared pair of electrons (tend to be
non-metals to non-metals)</div>

<div><br></br></div>

<div>Atoms want to have 8 valence electrons (or more
stable shells) and will share electrons with other atoms – unlike ionic bonds
where one is willing to give up electrons and the other is willing to accept,
covalent bonds tends to happen between atoms that don’t want to give up
electrons because they would then be left unstable, so they share electrons
instead&nbsp;</div>

Question 62

What are polyatomic ions?

Answer 62

<div>Combination of ionic and covalent bonding is
found in compounds that contain <b>polyatomic ions </b>– these are ions that
are covalently bonded groups of atoms that carry a net electrical charge&nbsp;</div>

<div><br></br></div>

<div>Common polyatomic ions are negatively charged (except for NH₄⁺)</div>

Question 63

What is VSEPR? 

Answer 63

<div><b>VSEPR (Valence-shell electron-pair repulsion
theory) </b>– electron pairs in the valence shell of an atom are repelled by
other electron pairs and get as far away from one another as possible</div>

<div><br></br></div>

<div>When the VSEPR theory is applied to the
valence-shell electrons of a central atom, the shape of the molecule or ion
containing the atoms can be predicted – two rules are followed: </div>

<div><ol><li>All
valence-shell electron pairs around the central atom are counted equally,
regardless of whether they are bonding or nonbonding pairs</li><li>Double
or triple bonds between atoms are treated like a single pair of electrons when
predicting shapes&nbsp;</li></ol><div>The electron pairs around a central atom will orient themselves in a space to get as far away from one another as possible</div></div>

<div><div><ul><li>Thus, two pairs will be oriented with one pair
on each opposite side of the central atom </li><li>Three pairs will form a triangle around the
central atom </li><li>Four pairs will be located at the corners of a
regular tetrahedron with the central atom in the center&nbsp;</li></ul></div>

</div>

Question 64

What is the difference between ionic and covalent bonds?

Answer 64

In ionic bonds, two atoms join because their is a transfer in electrons. One atom will give up electrons while the other accepts them. Both of them become charged atoms, or ions, and the electrostatic force pulls them together (positive + negative). Thus, they are formed through the transfer of electrons. <br></br><br></br>Covalent bonds are when atoms share molecules. 

Question 65

What is the difference between nonpolar and polar covalent bonds?

Answer 65

Nonpolar Covalent – there is equal sharing of electrons (the change in electronegativity is 0 – both have the same electronegativity <br></br><br></br>Polar Covalent – there is an unequal sharing of electrons (the change in electronegativity is between 0 and 2.1)

Question 66

Polar Covalent Bonds 

Answer 66

Molecules where one side is partially positive and the other side is partially negative, it is a polar bond. The electrons are unequally distributed. The more electronegative atom requires a partial negative charge and the less electronegative atom has a partial positive charge. 

Question 67

Electronegativity Charges for Polar, Nonpolar, and Ionic Bonds

Answer 67

<img></img><br></br><br></br>Electronegatively increases from left to right and decreases from top to bottom. <br></br><br></br>

Question 68

What are the rules for naming a binary covalent compound? 

Answer 68

<div><ol><li>Give the name of the less
electronegative element first (the element given first in the formula)</li><li>Give the stem of the name of the
more electronegative element next and add the suffix <b><i>-ide</i></b></li><li>Indicate the number of each type
of atom in the molecule by means of the Greek prefixes (see table below)&nbsp;</li></ol></div>

<div><br></br></div>

<div><div>
<table>
<tbody><tr>
<td>
<div><b>Number</b></div>
</td>
<td>
<div><b>Prefix</b></div>
</td>
</tr>
<tr>
<td>
<div>1</div>
</td>
<td>
<div><i>mono-</i></div>
</td>
</tr>
<tr>
<td>
<div>2</div>
</td>
<td>
<div><i>di-</i></div>
</td>
</tr>
<tr>
<td>
<div>3</div>
</td>
<td>
<div><i>tri-</i></div>
</td>
</tr>
<tr>
<td>
<div>4</div>
</td>
<td>
<div><i>tetra-</i></div>
</td>
</tr>
<tr>
<td>
<div>5</div>
</td>
<td>
<div><i>penta-</i></div>
</td>
</tr>
<tr>
<td>
<div>6</div>
</td>
<td>
<div><i>hexa-</i></div>
</td>
</tr>
<tr>
<td>
<div>7</div>
</td>
<td>
<div><i>hepta-</i></div>
</td>
</tr>
<tr>
<td>
<div>8</div>
</td>
<td>
<div><i>octa-</i></div>
</td>
</tr>
<tr>
<td>
<div>9</div>
</td>
<td>
<div><i>nona-</i></div>
</td>
</tr>
<tr>
<td>
<div>10</div>
</td>
<td>
<div><i>deca-</i></div>
</td>
</tr>
</tbody></table></div></div>

Question 69

What are the polyatomic ions for sulfate and phosphate?

Answer 69

Sulfate: SO₄^2-<br></br>Phosphate: PO₄^3-

Question 70

Differences between covalent, metallic, and ionic bonds and their relative strength to each other

Answer 70

Covalent bonds (strongest): Nonmetal – Nonmetal<br></br>Metallic bonds (next strongest): Metal – Metal<br></br>Ionic bonds (weakest): Nonmetal – Nonmetal 

Question 71

Types of bonds and relative strength 

Answer 71

<img></img>

Question 72

Differences between decomposition, combination, and replacement reactions

Answer 72

<div><b>Decomposition reactions </b>are when a single
substance is broken down to form two or more simpler substances (AB --&gt; A + B) -- typically requires a catalyst&nbsp;</div>

<div><div><b><br></br></b></div><div><b>Combination reactions </b>or synthesis reactions and is when two or more substances react
to form a single substance (A + B --&gt;&nbsp;&nbsp;C)</div></div>

<div><br></br></div>

<div><div><b>Single-replacement reactions </b>or
substitution reactions, are always redox reactions and take place when one
element reacts with a compound and displaces another element from the compound
(A + BX --&gt; B + AX)</div></div>

<div><br></br></div>

<div><div><b>Double-replacement reactions</b>, also called
metathesis reactions, are never redox reactions and is a chemical reaction in
which two compounds react and exchange partners to form two new compounds (AX +
BY --&gt; BX + AY)</div></div>

Question 73

Describe oxidation and reduction in redox reactions and the corresponding agents 

Answer 73

OIL RIG<br></br><br></br>Oxidation is losing electrons and are reducing agents<br></br>Reduction is gaining electrons and are oxidizing agents <br></br><br></br>In those atoms that are being reduced, they DECREASE in oxidation number 

Question 74

What are the redox rules? 

Answer 74

<div><ul><li>Element by itself is 0 [Eg,
Cl₂, Na, S₆, are always 0]</li><li>Monoatomic ion = the ion charge [e.g., K+
(+1), N^3- (-3), Mg²⁺(+2)]</li><li>Group IA – Always +1 [e.g.,&nbsp;KCl
(K = +1)]</li><li>Group IIA – Always +2</li><li>Halogens (7A) – usually -1, but positive with
oxygen</li><li>Hydrogen – is +1 with nonmetals and -1 with
metals</li><li>Oxygen – usually -2 but is -1 in peroxide (H₂O₂)</li><li>Sum of ON’s for a neutral compound = 0</li><li>Sum of ONs for a polyatomic ion = ion charge&nbsp;</li></ul></div>

Question 75

How do you solve a limiting reactant problem?

Answer 75

<img></img><br></br>First, you must convert from grams to moles, moles to moles, and then moles to grams<br></br><br></br>1. Calculate the amount of product that can be formed by the initial amount of each reactant <br></br>1.A. The reactant that gives the smaller amount of product is the limiting reactant<br></br>1.B. The smaller amount of product is the amount that will be formed when the limiting reactant is used up<br></br><br></br>2. Calculate the amount of the non-limiting reactant that is needed to use up the limiting reactant<br></br><br></br>3. Subtract the amount of non-limiting reactant needed to use up the limiting reactant from the original amount of non-limiting reactants – the difference is the excess amount of the non-limiting reactant <br></br>

Question 76

What is a reaction yield and how do you calculate it?

Answer 76

Reaction yield refers to the amount of product obtained in a chemical reaction. <br></br><br></br>It is calculated by dividing the actual yield by the theoretical yield x 100. <br></br><br></br>% yield = actual yield / theoretical yield x 100

Question 77

[sound:rec1733196824.mp3]<br></br>部屋にエアコンはありますか？

Answer 77

Y a-t-il la climatisation dans la pièce ?

Question 78

<img></img><br></br><b>Acetylsalicylic acid</b>/<b>aspirin </b>is a white solid melting at 136 degrees C. If heated gently, a gas is given off. After the gas stops, a white solid remains melts at a temperature different from 136 degrees C. <br></br><br></br>Is the white solid that remains after heating still aspirin? Explain your answer. 

Answer 78

No. It must be different because its melting point is different from that of aspirin. 

Question 79

<img></img><b><br></br>Acetylsalicylic acid</b>/<b>aspirin </b>is a white solid melting at 136 degrees C. If heated gently, a gas is given off. After the gas stops, a white solid remains melts at a temperature different from 136 degrees C. <br></br><br></br>In terms of the number of atoms contained, how will the aspirin molecule’s size compares with the molecules’ sizes of the resulted white solid?

Answer 79

The aspirin molecules must be larger because the atoms of the aspirin were divided between the molecules of the new solid and the molecules of the evolved gas.

Question 80

<img></img><b><br></br>Acetylsalicylic acid</b>/<b>aspirin </b>is a white solid melting at 136 degrees C. If heated gently, a gas is given off. After the gas stops, a white solid remains melts at a temperature different from 136 degrees C. <br></br><br></br>Classify aspirin molecules by using the term homoatomic or heteroatomic. Explain. 

Answer 80

Heteroatomic, because the aspirin changed into two different substances, molecules of aspirin must contain at least two different kinds of atoms. 

Question 81

Is liquid eye drops a homogeneous or heterogeneous mixture?

Answer 81

homogenous

Question 82

Is aspirin tablet a homogeneous or heterogeneous mixture? <br></br><br></br>Aspirin tablet

Answer 82

homogenous

Question 83

Is urine sample with kidney stones a homogeneous or heterogeneous mixture?

Answer 83

heterogeneous

Question 84

Is petroleum jelly a homogeneous or heterogeneous mixture?

Answer 84

heterogenous