Video Transcript
Give the chemical symbols of the
two alkaline earth metals that produce orange-red or red flames in a flame test.
A flame test is when we burn a
substance and use the resulting color of the flame to identify the metal ion in the
substance. The alkaline earth metals are the
elements found in the second column, also known as group two, of the periodic table
of the elements. The names of the alkaline earth
metals are beryllium, magnesium, calcium, strontium, barium, and radium. To answer this question, we need to
find the flame colors of these six elements. Then, we need to determine which
ones are orange red or red and give the chemical symbols of those two elements.
First, the element radium is rare
and radioactive, so we can ignore it for the purposes of this problem. Barium provides a green flame;
strontium, a red flame; calcium, an orange-red flame; and magnesium and beryllium
provide no color to the flame in the flame test. Why is that? Well, for other elements, colored
light is released when their electrons, which have been excited by heat energy,
return back down to their original energy levels. For beryllium and magnesium, it
takes more energy than the flame can provide to excite their electrons. So the electrons stay put and do
not release light energy.
So, with all of the colors in front
of us, we can see that two of the elements, calcium and strontium, give us the red
or orange-red color that we’re looking for. Keep in mind that the question asks
for the chemical symbols of the metals. So in our final answer, we want to
write Ca and Sr. Those are the two chemical symbols of the two alkaline earth metals
that produce orange-red or red flames in a flame test.
