Question

chemists can identify the composition of some unknown salts by conducting a flame test. when potassium salts are heated in a flame, a purple color is observed. this is due to the movement of electrons between energy levels. what is the electron configuration of a potassium atom at ground state?
1s²2s²2p⁶3s²3p⁶3d¹
1s²2s²2d⁶3s²3d⁶4s¹
1s²2s²2p⁶3s²3p⁶4d¹
1s²2s²2p⁶3s²3p⁶4s¹
4
multiple choice 1 point
which statement best describes the name and location on the periodic table of the elements with the highest and lowest electronegativity, respectively?
neon, on the upper right, has the highest electronegativity, and francium, on the lower left, has the lowest electronegativity.
helium, on the upper right, has the highest electronegativity, and francium, on the lower left, has the lowest electronegativity.
fluorine, on the upper right, has the highest electronegativity, and francium, on the lower left, has the lowest electronegativity.
hydrogen, on the upper left, has the highest electronegativity, and radon, on the lower right, has the lowest electronegativity.

Explanation:

• For the electron - configuration of potassium:
• Potassium has an atomic number of 19. Using the Aufbau principle (filling orbitals in order of increasing energy: \(1s<2s < 2p<3s<3p<4s<3d\)), we fill the orbitals.
• \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}\) is the correct configuration as after filling \(3p\) (which can hold 6 electrons), the next electron goes to the \(4s\) orbital (lower energy than \(3d\) for filling in the ground - state of potassium).
• For electronegativity:
• Electronegativity generally increases across a period (from left to right) and decreases down a group.
• Fluorine (in group 17, period 2, upper - right region of the periodic table) has the highest electronegativity. Noble gases (like Neon and Helium) have very low electronegativity as they have a stable electron configuration and do not tend to gain electrons easily. Hydrogen has a relatively low electronegativity compared to fluorine.
• Francium (in group 1, period 7, lower - left region) has a very low electronegativity as it is a large atom and tends to lose electrons easily. Radon is a noble gas and has a low electronegativity, but Francium has a lower electronegativity than Radon.

Answer:

For the electron - configuration of potassium: \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}\) (the fourth option).
For the electronegativity statement: Fluorine, on the upper right, has the highest electronegativity, and Francium, on the lower left, has the lowest electronegativity (the third option).