What element has 21 neutrons, 20 electrons and 20 protons

What are two ways that isotopes of an element differ?

Microwaves, such as those used for radar and to heat food in a microwave oven, have wavelengths greater than about 3 mm. What is the frequency of radiation of wavelength 3.63 mm? Answer in units of s-1.

Which of these elements in group 1A has the largest atomic radius?

The feel, appearance, or consistency of a surface, substance, or fabric?

Which of the following best explains why you sanded the copper wire before burning it? to create less friction between the copper and the tongs to make sure that copper metal was exposed on the surface of the wire to make the copper wire flammable

Find the molar mass of potassium dichromate, K2Cr2O7

Zn (s) + cu2 + (aq) →zn2 + (aq) + cu (s). part a under standard conditions, what is the maximum electrical work, in joules, that the cell can accomplish if 51.0 g of copper is plated out?

13 This word describes the circulatory system that provides nutrients and oxygen to living cells of the body.

Write the outer electron configuration for the group 15 element in the fourth period.

Describe the relationship between transmittance and the absorbance?