Science Test 12/12
How many covalent bonds would the following atom usually form?
3
How many atoms are in one molecule of Na2SO4?
7
What is a molecule?
A group of atoms held together by covalent bonds.
What needs to be done to convert a neutral nitrogen atom into an N-3 species?
Add three electrons
Which of the following is a positive ion? Mg+2, Na+1, Ca+2, Al+3
All of the above
What is the main difference between a dipole-dipole interaction and a dipole-induced dipole interaction?
Both are similar, but one involves a temporary dipole created by permanent dipole.
Is the following transformation representative of a physical change or a chemical change?
Chemical change because the atoms are connected differently.
Classify the following bonds as ionic, covalent, or neither (O, atomic number 8; F, atomic number 9; Na, atomic number 17; U, atomic number 92).
Covalent,ionic,neither
Which of the following is the correct electron dot structure for chlorine(atomic no.=17)?
D
The separation of charges within a polar molecule is called a(n) ________.
Dipole
Which of the following molecules contains a polar bond?
H-F
Which of the following molecules would contain a dipole?
H-F
For the following balanced equation, which has the highest coefficient? 4 H2 + 2 C → 2 CH4
H2
Why are the melting temperatures of most ionic compounds far greater than the melting temperatures of most covalent compounds?
Ionic bonds are so much stronger than the molecular attractions between covalently bonded compounds.
What is a reaction rate?
It is the speed at which reactants are consumed or product is formed.
The circles in the boxes shown above represent the submicroscopic particles of a material in its three phases. From left to right these are
Liquid,solid,Gas
The atoms of materials that conduct electricity best tend to be held together by
Metallic Bonds
Which of the following elements has two electrons in the last energy level?
Mg
Which of the following elements will most likely form an ion with a +2 charge?
Mg
Which of the following molecules contains an ionic bond?
MgCl2
Which molecule is most polar?
O=C=S
Which of the following best describes ionic bonding?
One atom giving up some of its electrons to another form.
What is wrong with the following depiction of chemical reaction
One box contains more atoms than the other
What is the main difference between an ionic and a covalent bond?
One is sharing a pair electrons, the other is the transfer of at least
Which of the following is a correctly balanced equation? A) 1 P4 + 6 H2 => 4 PH3 B) P4 + 3 H2 => PH3 C) P4 + 6 H2 => 4 PH3 D) 2 P4 + 12 H2 => 8 PH3
P4 + 6 H2 => 4 PH3
Why doesn't the sodium atom gain seven electrons so that its third shell becomes the filled outermost shell?
Sodium's nuclear charge is not strong enough to hold that many more electrons.
If an ionic bond is stronger than a dipole-dipole interaction, how can water dissolve an ionic compound?
The ion-dipole interactions of a bunch of water molecules gang up on the strong ionic bond and pull it ingo the solution.
Why is metal shiny?
The loose electrons reflect most wavelengths of light
Why might increasing the temperature alter the rate of a chemical reaction?
The molecules will have a higher kinetic energy and bump into one another harder.
How is the number of unpaired valence electrons in an atom related to the number of bonds that the atom can form?
The number of unpaired valence electrons in an atom is the same as the number of bonds that the atom can form.
The neon atom tends not to gain any additional electrons because
There is no more room available in its outermost occupied shell.
Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why?
They have a great tendency to lose electrons.
What is a chemical reaction?
When one or more new compounds are formed be rearranging atoms.
Given the following generic chemical reaction, which is the product? X==>Y
Y is the Product
Why might increasing the concentration of a set of reactants increase the rate of reaction?
You have increased chances that any two reactant molecules will collided and react.
Which of the following is the strongest? A) an ion- dipole attraction B) an induced dipole-induced dipole attraction C) A chemical bond D) a dipole-induced dipole attraction E) a dipole- dipole attraction
a chemical bond
Molecular oxygen, O2, and ozone, O3, are both examples of
elements
The concept of a chemical bond
how two or more atoms are held together
A chemical change results in
new materials
What is activation energy?
the minimum amount of energy needed to start a chemical reaction
