Answer:
The correct answer is <em>D) Niels Bohr</em>
Explanation:
Bohr proposed a new atomic model, whereby he explains that electrons rotate around the nucleus at well-defined levels, describing circular orbits. Each orbit was called the energy level (it is called the main quantum number n, going from numbers 1 to 7). To make his model, Bohr studied the Hydrogen atom (it has a proton in its nucleus and an electron rotating around it).
The answer is enough solvent to make 1.00 L of solution. Since molarity is the number of moles of solute in one liter of solution, adding 0.500 mole solute to one liter solvent might not result to a solution with one liter total volume. Less than one liter solvent is first added to dissolve 0.500 mole solute and then the solution is carefully filled with more solvent until the solution reaches to one liter total volume. Hence, the resulting solution is a 0.500M concentration.
He Rydberg formula can be extended for use with any hydrogen-like chemical elements.
<span>1/ λ = R*Z^2 [ 1/n1^2 - 1/n2^2] </span>
<span>where </span>
<span>λ is the wavelength of the light emitted in vacuum; </span>
<span>R is the Rydberg constant for this element; R 1.09737x 10^7 m-1 </span>
<span>Z is the atomic number, for He, Z =2; </span>
<span>n1 and n2 are integers such that n1 < n2 </span>
<span>The energy of a He+ 1s orbital is the opposite to the energy needed to ionize the electron that is </span>
<span>taking it from n = 1 (1/n1^2 =1) to n2 = ∞ (1/n2^2 = 0) </span>
<span>.: 1/ λ = R*Z^2 = 1.09737x 10^7*(2)^2 </span>
<span>λ = 2.278*10^-8 m </span>
<span>E = h*c/λ </span>
<span>Planck constant h = 6.626x10^-34 J s </span>
<span>c = speed of light = 2.998 x 10^8 m s-1 </span>
<span>E = (6.626x10^-34*2.998 x 10^8)/(2.278*10^-8) = 8.72*10^-18 J ion-1 </span>
<span>Can convert this value to kJ mol-1: </span>
<span>(8.72*10^-18*6.022 x 10^23)/1*10^3 = 5251 kJ mol-1 </span>
<span>Lit value: RP’s secret book: 5240.4 kJ mol-1 (difference is due to a small change in R going from H to He+) </span>
<span>So energy of the 1s e- in He+ = -5251 kJ mol-1</span>
Answer:
positively charged nucleons are 24
Explanation:
Given element:
₂₄⁵⁰ Cr
The superscript before the symbol of the atoms is mass number
The subscript before the symbol is the atomic number
Cr is the symbol of the atom
Now,
Atomic number is the number of protons in an atom.
The protons are the positively charged particles in an atom.
For this specie, the positively charged nucleons are 24
