The scientist which was credited with first stating that electrons orbit an atomic nucleus was Niels Henrik David Bohr. He was the proponent of the Bohr model of the atom, wherein he states that energy level of electrons are distinct and that electrons revolve on stable orbits within the atomic nucleus but can actually transfer from one orbit (level) to another. The orbitals are called: s, p, d and f orbitals.
Think of it this way: it is a distribution problem in which you are multiplying the 2 on the outside with each element in the parentheses. Oxygen does not have a number in front of it, so put an imaginary one in front of it to help you. Do the same with Hydrogen since it doesn't have a number in front of it either. Now you know that hydrogen has one ion and oxygen has one... but you must now multiply each of the elements' ions by two. You should now know that Oxygen has 2 ions in Calcium Hydroxide and that there are also 2 ions of Hydrogen in Calcium Hydroxide. Does this make sense?
Answer:
1.68 × 10²³ Molecules
Explanation:
As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of particles (molecules) contained by 0.280 moles of Br₂, we will use following relation,
Moles = Number of Molecules ÷ 6.022 × 10²³ Molecules.mol⁻¹
Solving for Number of Molecules,
Number of Molecules = Moles × 6.022 × 10²³ Molecules.mol⁻¹
Putting values,
Number of Molecules = 0.280 mol × 6.022 × 10²³ Molecules.mol⁻¹
Number of Molecules = 1.68 × 10²³ Molecules
Hence,
There are 1.68 × 10²³ Molecules present in 0.280 moles of Br₂.
Answer:
Here's what I find.
Explanation:
Many scientists contributed to our model of the atom.
Among those who received the Nobel Prize for their work are:
1906 — J.J. Thomson — discovery of the electron
1908 — Ernest Rutherford — nuclear model of the atom
1922 — Niels Bohr — planetary model of the atom
1922 — Albert Einstein — quantum mechanical model of the atom
1935 — James Chadwick — discovery of the neutron
