Chemistry Chapter 2 Test Flashcards
Describe the difference between an element and a compound.
An element is something pure that cannot be broken down into simpler substances; made of one type of atom.
A compound is a combination of elements in a specific ratio; composed of atoms of two or more atoms.
What is meant by physical form?
Physical form means state of matter (solid, liquid, gas) or if the substance has been dissolved in water (aq).
What is the difference between NaOH (s) and NaOH (aq)?
NaOH (s) is in a solid state
NaOH (aq) is in a liquid state (dissolved in water)
How many elements are included in the chemical formula for sodium nitrate, NaNO3?
Name them and how many atoms of each?
Three elements; sodium, nitrogen and oxygen
Na – 1 N- 1 O - 3
Explain what a chemical reaction is. What are some possible signs that a chemical reaction is taking place?
A chemical reaction changes the bonds in a compound.
Some indications of a chemical change are bubbling, color change, gas produced, heat produced, or light is given off.
Explain what a physical change is. What are some possible signs of a physical change?
A physical change affect the form of a substance and are usually reversible
Indications of a physical change are change in shape and size.
Determine if the following examples are a physical or chemical change.
a. apple is cut
b. pancakes are cooked
c. milk sours
d. iron rusts
e. wood rots
f. ice melts
a. physical
b. chemical
c. chemical
d. chemical
e. chemical
f. physical
Explain the law conservation of matter in your own words.
The Law of Conservation of Matter states that matter cannot be created nor destroyed, it can only change forms.
How can chemical names and symbols help you figure out what copper compound was made in each step of the copper cycle? Give an example.
Each name and formula is unique to the compound, so we know exactly what it is made of.
Ex: Cu(OH)2 is Copper Hydroxide
List three properties of the elements that are useful in sorting the elements.
Reactivity
Formulas in Chemical Compounds
Atomic Mass
Do you expect carbon, C, to be more similar to nitrogen, N, oxygen, O, or silicon, Si? Why?
Carbon will be most similar to silicon because they are in the same group.
Suppose you have equal amounts of calcium, Ca, in two beakers. In one beaker, you react the calcium with oxygen, O. In the other beaker, you react the calcium with sulfur, S. The reaction with oxygen forms the compound calcium oxide, CaO.
a. What do you predict is the chemical formula of the compound formed from the reaction between calcium and sulfur?
b. Which compound has more mass, the compound containing calcium and oxygen, or the compound containing calcium and sulfur? Explain your thinking.
a. CaS (S is in the same group as O, so it reacts with Ca the same way)
b. CaS has more mass because Sulfur is a heavier atom than oxygen
Ca mass 40.078 + S mass 32.066 = CaS mass 72.144 Ca mass 40.078 + O mass 15.9994 = CaO mass 56.0774
Find iodine, I, on the periodic table.
a. Find iodine’s atomic number, average atomic mass, period, and group.
b. Is iodine a metal, metalloid, or nonmetal? How can you tell?
c. Which would be more reactive: Iodine or Chlorine? Explain.
a.
Atomic Number: 53
Mass: 126.9 amu
Group: 17
b. Nonmetal; it is to the right of the staircase line
c. Chlorine is more reactive because it is closer to Fluorine, and Fluorine is the most reactive nonmetal.
Name two elements that have properties similar to those of beryllium, Be, and have average atomic masses higher than 130.
Barium and radium have similar properties to Beryllium because they are in the same group.
Which of these elements are metals?
a. Fluorine, Fl d. Titanium, Ti
b. Lead, Pb e. Oxygen, O
c. Potassium, K f. Silicon, Si
b, c, d
*All are to the left of the staircase
