Which statements describe molecules? Check all that apply.

Molecules are made of two or more atoms.
Molecules are all the same size
Molecules range in size.
Molecules are only made of atoms of the same element.
Molecules are only made of atoms of different elements.
Molecules are made of atoms of the same element or different elements.

Compare and contrast the bohr model and the electron cloud models of the atom.

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.