Unit 0 (Basics)
Chemistry is the study of...
matter and energy and their interactions.
The charge of a proton is ____. It is located in the _____.
Positive
Nucleus
Where do you locate how many grams are in a mole of a substance?
The periodic table (atomic/molar mass)
Draw a lewis structure for N. How many bonds can it make?
N has 5 dots. 3 are single (3 bonds can be made).
What is the difference between a chemical and physical change?
Chemical = making a new substance (rearranging atoms, making new bonds)
Physical = changing the way something looks, not what it is
Which is conserved? Matter or energy?
Both!
Fe has ___ protons and ____ electrons.
26 protons
26 electrons
Which corner of the periodic table has the strongest electronegativity? (What is the trend?)
Top right. Electronegativity increases up and to the right.
What bond type shares electrons?
Covalent
What are the 4 main signs of a chemical reaction?
color change
temp change
formation of a solid (precipitate)
formation of a gas (bubbling)
Draw a direct relationship on a graph.
Draw an inverse relationship on a graph.
Direct = positive slope.
Inverse = negative slope.
I has ____ neutrons.
74 neutrons (127-53)
Metals are most reactive in which corner of the PT?
Nonmetals are most reactive in which corner of the PT?
Metals - bottom left
Nonmetals - top right
Balance AND identify the type of reaction below.
__Fe + __O2 --> __Fe2O3
4, 3, 2
Synthesis
What is an independent variable and where does it go on a graph?
What is a dependent variable and where does it go on a graph?
IV = what YOU change, x-axis
DV = what you are observing / measuring, y-axis
Draw a bohr model for B.
How many valence electrons does it have?
middle (nucleus) = 5 protons, 6 neutrons
first energy level = 2 electrons
second energy level = 3 electrons (valanece)
How many grams are there in 2.5 moles of MgCl2?
238.03 g MgCl2.
What are the properties of a covalent substance?
Melting point = high or low?
Dissolve in water = yes or no?
Dissolve in alcohol = yes or no?
Conductivity in water = ?
Melting = low temp / fast
Dissolve in water = generally no
Dissolve in alcohol = yes
Conductivity = no
Balance AND identify the type of reaction below.
__Na2SO4 + __SrCl2 --> __NaCl + __SrSO4
1, 1, 2, 1
Double Replacement
How can you observe conservation of matter?
...conservation of energy?
Matter - take the mass before and after a change.
Energy - observe the different types of energy transfers
No. All elements have their own unique line spectra because they all have different energy levels and amounts of electrons that absorb/emit different amounts of energy (different wavelengths/colors of light).
Explain why the trends get stronger.
1. Metals get more reactive when ___.
2. Nonmetals get more reactive when ___.
3. Atomic radius get bigger when ___.
4. Electronegativity gets stronger when ____.
1. Metals get more reactive when they are able to get rid of electrons easier.
2. Nonmetals get more reactive when they get gain electrons more easily.
3. Atomic radius gets bigger when there are more energy levels and less protons.
4. Electronegativity gets stronger when there are less energy levels and more protons to pull electrons in.
Draw the lewis structure for COS.
C is double bonded to S and O. Both S and O have 2 lone pairs.
Balance AND identify the type of reaction below.
__H2CO3 --> __CO2 + __H2O
1, 1, 1
Decomposition