1. B

    Elements and Substances

    Hey guys, I am new to chemistry and I am having a lot of trouble understanding the what elements and substances are. In the IUPAC Gold Book, an element is defined as a species of atom defined by the number of protons, but it also says that an element is a substance composed of the same type of...
  2. M

    Dissociation Question

    I was doing a problem where MgF2 dissociated to Mg and 2F. Since F is a super 7, why did it dissociate to 2F instead of F2? Is there a general rule to know what form the super 7 elements will dissociate in? PS This was a Ksp question and as such, the coefficient matters because if it's 2F I...
  3. P

    Sun elements

    Have we discovered all of the sun's elements? Yes or no and why? I am struggling with this one....
  4. I

    What are the importance of studying elements?

    Does anyone have the better answer? i need at least four (4) importance's.. please help...
  5. L

    Atomic radii of elements

    The atomic radii of Y (180pm) and La (187 pm) are significantly different, but the radii of Zr (160 pm) and Hf (159 pm) are essentially identical. Explain?