Given the following pairs of elements, predict whether they will form a bond that is primarily ionic or covalent.   be able to explain lithium and oxygen fluorine and chlorine calcium and sulfur

If there is a great difference in electromagnetic values, then the molecule will be primarily ionic. typically this is 0.3+

if there is a small difference in electromagnetic values, then the molecule will be primarily covalent. typically this is <0.3

you can find the differences by looking at a periodic table, using the given electromagnetic values, and using simple subtraction

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant. 

Higher temperature = molecules move around faster. and vice versa.