Answer:
From Top to Bottom:
- Democritus coming up with the concept of an atom
- Dalton discovering that atoms are the smallest part of an element
- Rutherford discovering the nucleus of an atom
- Thomson discovering electrons
- Bohr modeling electrons orbiting the nucleus
- Schrodinger modeling electrons in the electron cloud
Explanation:
The best way to think about this is from the inside out. Democrats (who lived long before any of the other scientists mentioned) was the one who thought of the idea of the atom. - Therefore, this must be first because all other choices are elaborations on the idea that atoms exist. Next must be Dalton. Dalton saw atoms as "cannonballs" if you will; a solid mass. So then after that, Rutherford and his gold foil experiment (he discovered that some rays he shot through gold foil were deflected back; ie the existence of concentrated areas in an atom, ie the nucleus). Then we get into the information on electrons. We must start with discovery (Thomson). Heres where it gets complicated. Electrons don't <em>actually </em>orbit the nucleus, they exist in electron clouds. So it would be Bohr, who came up with the idea that electron exist outside the nucleus, then Schrodinger, who elaborated on Bohr's theory. Hope this helps!
Nat, Junior
Accel + AP Chem student
Answer:
C. the number of atoms, molecules, ions, formula units, or other particles in a mole of a substance
Explanation: Its correct
A. 1/2
Explanation- There is a 5/10 chance of choosing on of the numbers which simplifies to 1/2
Al(NO3)3(aq) + 3NaOH(s) --> Al(OH)3 (s) + 3NaNO3 (aq)
The precipitate here is Al(OH)3 (s), since the solid reactant is the precipitate in the aqueous solution. Usually, it is okay to assume in basic chemistry that the transition metal is going to be part of the compound that is the precipitate, especially in an acidic salt and a strong base reaction that we have here.
It is energetically favorable for all atoms to have a complete outer
electron shell. Loosely, the atoms on the left hand side of the periodic
table only have a few extra electrons in their outer shell so it is
energetically favorable for them to lose them. The atoms on the right
hand side of the periodic table almost have enough electrons in their
outer shell and so they have a tendency to gain them.
Once electrons have left an electron shell, an atom will have a positive
charge because it has more protons (positive charges) than electrons
(negative charges). Similarly, an electron which has gained electrons to
complete its outer shell will have a negative charge because it now has
more electrons (negative charge) than protons (positive charge).