Atomic Structure
What are the three subatomic particles that make up the atom? What are their charges?
Protons - +1
Neutrons - 0
Electrons - -1
Suppose you have an isotope with percent abundance of 65%. You know there is only one other isotope, what is the percent abundance of that other isotope?
Since the first one makes up 65% of all of that element and there is ONLY one other, it makes up the remainder part that makes up the whole OR:
100% - 65% = 35%
What are the three main categories we can classify elements?
Metal, Nonmetal, and Metalloid
In any card or box, what is listed on the card of an element?
In any element card (from top to bottom):
Atomic number (top) - number of protons
Element symbol (1-2 letters with the first letter being capital and the second letter is lowercase)
Element name
Average Atomic Mass - expected mass of an atom of that element
To determine the number of neutrons in an atom, you must:
Round the average atomic mass and subtract the number of protons (or atomic number)
What is needed to calculate average atomic mass?
Average mass (or mass of an isotope)
Percent abundance of each isotope
Metals and nonmetals are considered _____ due to their properties.
opposites -- consider the different properties of metals, nonmetals, and metalloids we have studied:
To see this, consider the following:
Metals are good conductors of heat & electricity, whereas nonmetals are poor conductors of heat and electricity.
Metals have high melting points whereas nonmetals have lower melting points.
Metals are malleable (dent/flatten) when hit whereas nonmetals are brittle (break/shatter).
Metals are shiny whereas nonmetals are dull.
With your hands, describe the difference between a group and a period.
A group is a column (vertical entry of boxes) on a table, whereas a period is a row (horizontal entry of boxes).
On a blank atom, explain the regions of the atom. Which subatomic particle goes where?
For the ring portion, what is the maximum number each can hold?
In the center is the nucleus and the rings surrounding the nucleus is called energy levels or shells.
The first energy level can hold 2 electrons.
The second energy level can hold 8 electrons.
The third energy level can hold 8 electrons.
Suppose that an element has 3 isotopes with masses 61, 63, and 67. Without knowledge of the percent abundances, which of the following is a possible average atomic mass:
a) 60
b) 60.7
c) 67.1
d) 65
65 - it is the only value that falls between your lowest and highest value listed.
Name all traits of nonmetals and all traits of metals.
Metals traits:
- Mostly solids at room temperature.
- Good conductor of heat and electricity.
- Malleable
- Ductile
- Has Luster (or metallic luster -- appears shiny/reflective, etc.)
- Generally have higher M.P.
Nonmetal traits:
- Mostly nonmetal at room temperature.
- Poor conductor of heat and elecricity.
- Brittle
- Dull (or color-less)
- Generally have lower M.P. on average.
What element(s) are in group 2?
Alkaline earth metals (you can list out the entire group which includes: Be, Mg, Ca, Sr, Ba, and Ra.)
What is always true of the number of electrons in a neutral atom? Why is that the case?
Suppose the atom is not neutral, what do we call the atom and why? What are the two separate categories?
If the atom is NOT neutral, the atom is an ion. There becomes a net charge (more p+ than e- or vice-versa). If it has more p+ than e-, it is positive charged (or a cation) and if it has more e- than p+, it is negatively charged and it is an anion.
Using the following information about these isotopes, calculate the average atomic mass:
Isotope % Abundance
Si-28. 92.23
Si-29 4.67
Si-30 3.10
We following the formula:
(mass of isotope 1) (% Abudance isotope 1) + (mass of isotope 2) (& Abundance isotope 2)+.... for however many isotopes
(28)(0.9223)+(29)(0.0467)+(30)(0.0310)
Suppose that an element is found to be:
brittle
good conductor of electricity and heat
has luster
What can we classify it as?
Metalloid is the ONLY class that will have a mixture of properties that come from metal and nonmetals. Brittle is a nonmetal trait, whereas having luster and being a good conductor of heat and electricity are traits of a metal. Having a combination of both traits means that this element sample must be a metalloid.
Metals are located to the _____ whereas nonmetal are are located to the ______ of the staircase.
left, right (first then second blank)
Using a blank atom, create the element Mg. Recreate the same element Mg with 2 fewer electrons and identify the type of ion with the net charge.
I will draw it out.
More p+ than e- is a cation and it will have a +2 charge (as it has 2 more protons than electrons).
Using the following information about these isotopes, it is given that the average atomic mass is 6.925.
Isotope % Abundance
Li-6 7.5
Li-X 92.5
What is the mass of the other isotope Li-X?
Set it up the normal way:
(6)(0.075)+(X)(0.925) = 6.925
X = 7
Why is it that pans are made of metal and NOT nonmetal? Come up with some reasons based on your understanding of properties of metal, nonmetal, and metalloid.
If a pan was solely made of a nonmetal,
*we would most likely have it at room temperature meaning that it should be in the gaseous state (you wouldn't cook using a pan in a volcano/Antarctica).
*since nonmetals are poor at conducting heat, it would take much longer for the pan to heat up if it were in the solid state -- it would take MUCH longer to cook on nonmetal pan than a metal pan.
*nonmetals have lower melting points than metals. Therefore, nonmetals can possibly melt since it can melt at a lower melting point where metals have higher melting points.
What is the only element that is part of the alkali metals (group 1) that is NOT part of the group?
Hydrogen - it is a nonmetal that is placed as an exception to the alkali metals.