How do you find the number of valence electrons in an element using the periodic table?

The clouds are grey and ground is wet. a quantitative b qualitative

This chart lists four kinds of polymers and their sources. what can be known about all four polymers, despite their differences? they come from living things. they share ionic carbon bonds. they are at least 100 monomers long. they are made of repeating subunits.

Calculate the number of kilojoules to warm 125 g of iron from 23.5°c to 78.0°c.