Video Transcript
Fill in the blank. Most metals contain blank electrons
in their outermost energy level. (A) More than four, (B) four, (C)
less than four, (D) more than five, (E) less than five.
To answer this question, we need to
choose the correct word or phrase to put in the blank to complete the statement. We can see from the answer choices
that we need to determine how many electrons metals tend to have in their outermost
energy level. Let’s clear the answer choices for
now so we can look at where the metals are located on the periodic table.
In this diagram of the periodic
table, the metals are shown in pink. We can see that most elements are
metals. Excluding the elements that have
unknown chemical properties, metals are found in groups 1 through 16. A group on the periodic table is a
vertical column. In this video, we will focus only
on the metals in groups 1 and 2 and those in groups 13 to 16.
A horizontal row on the periodic
table is called a period. In general, elements in the same
row have electrons located in the same energy levels. An energy level is a region that is
a certain distance from the nucleus of an atom and is where electrons are
located. Energy levels are also often called
electron shells. The first three energy levels
inside atoms are the K, L, and M energy levels. K is the energy level closest to
the nucleus.
Let’s find out how many electrons
are in the energy levels of the elements in period one and two on the periodic
table. Period one contains the elements
hydrogen and helium. The electrons of these two elements
are found in the K energy level. A hydrogen atom contains one
electron, and a helium atom contains two electrons.
The electrons of the elements in
period two are found in both the K and L shells. All of the elements in this period
have two electrons in the K shell, which is an inner shell. We notice that when we move from
left to right across the period, each atom has one more electron in the L shell when
compared to the atom before it.
Now, let’s take a look at the
elements in period three. All of these elements have two
electrons in the first energy level and eight electrons in the second energy
level. And just like in period two, the
first element has one electron in the outermost energy level and each element that
comes after has one more electron in its outermost energy level.
There is also another pattern to
notice. Elements that are in the same group
or column have the same number of electrons in their outermost energy level. For example, all the elements in
group 1 have one electron in the outermost energy level. The pattern continues as we move
across the periodic table group by group.
The last group contains the noble
gases. Noble gases have full outermost
energy levels. Helium’s only energy level has two
electrons, but all of the other noble gases below helium have eight electrons in
their outer energy level.
We notice that the metals, which
are outlined in pink here, have three or less electrons in their outermost energy
level. There are many more metals that we
are not showing here. But in general, metals like the
ones we are discussing in this video have less than four electrons in their outer
energy level. The elements boron and silicon,
outlined in green, are metalloids. And the elements outlined in orange
are nonmetals. The element hydrogen has one
electron in its outer energy level. And the element carbon has four
electrons in its outer energy level. However, most nonmetals have more
than four electrons in their outer energy level.
Now let’s bring the answer choices
back up on screen. We’ve learned that most metals have
less than four electrons located in their outermost energy level. Therefore, the answer that
correctly completes the statement is answer choice (C), less than four.
