Why did Mendeleev leave gaps

An atom has three full orbitals in its second energy level. How many electrons are present in the second energy level of the atom? 9 12 6 3

Uranium-232 has a half-life of 68.8 years. After 344.0 years, how much uranium-232 will remain from a 100.0-g sample? 1.56 g 3.13 g 5.00 g 20.0 g

Describe the different types of storms.

After owls eat, they throw up the undigested parts of their meals. These "pellets" contain the fur and skeletal parts of their prey. A student plans to look at an owl pellet to see which small vertebrates the owl ate.

Which indicator would show a pH change from 6 to 7? Red litmus indicator Methyl red indicator Phenol red indicator Blue litmus indicator

A fish company delivers 22 kg of salmon, 5.5 kg of crab and 3.48 kg of oysters to your seafood restaurant. What is the mass, in kilograms of the seafood? What is the total number of pounds?

If 38.7 grams of lithium chlorate decomposes, how many grams of oxygen gas can be produced?

Balance the following redox equation in acidic solution using the smallest integers possible and select the correct coefficient for the H + (aq) ion.

Toussaint L' ouveeture lead a revolt that eventually resulted in Independence for

If a solution contains 1 x 106 hb molecules, how many o2 binding sites are available? if the solution of hb is 50% saturated with o2, how many binding sites are occupied by o2?