横向
1
Mass per unit volume
4
Force that attracts objects together
6
The Red Planet
7
Unit of energy
11
Substance with pH below 7
13
Smallest unit of an element
纵向
2
Unit of electric potential
3
Compound containing oxygen
5
Gas form of a liquid
8
Form of thermal energy
9
Hottest planet in solar system
10
Path of a planet around the sun
12
Element found in all living things
14
Center of an atom or cell