1. ~Unknown

2. Perpendicular
So, as mentioned before electromagnetic waves are perpendicular.
What does perpendicular: It means that the waves cross each other at a 90 degree angle.

3. Electromagnetic waves….furthermore.
No require physical medium through which to spread and further to progress.
Unlike mechanical waves, such as sound, electromagnetic waves can travel through the empty vacuum of space.

4. Mechanical Waves
Waves of oscillation of matter that transfer energy through a medium. While waves can move over long distances, the movement of the medium of transmission (material) is limited.

5. What causes waves?
Some kind of initial vibration. Electromagnetic waves are caused by the vibrations of charged particles.

6. Charged particles?
Such as electrons and protons. Charged particles are surrounded by electric fields that exert forces on other charged particles.

7. Either a positive or negative
Atoms have charges
Either a positive or negative

8. Electronegativity Trend
From right to left the electronegativity increases. Meaning the more electrons on the outer valence shells the closer to the nucleus.