Some more chemistry/math questions.

Question

A) UV radiation has a wavelength of 1.00 x 10^-8 m. Calculate the energy of this radiation.

B) Three naturally occurring isotopes of potassium exist: K-39, K-40, and K -42. The average atomic mass of potassium is 39.102 AMU. Which is the most abundant isotope?

C) What is the correct symbol for an atom that contains 4 protons and 5 neutrons? 

D) Which of the following statements is not an idea from Dalton's Atomic Theory?

1. An element is composed of extremely small indivisible particles called atoms.
2. All atoms of a given element have identical properties which differ from those of all other elements.
3. Atoms can only be transformed into atoms of another element by nuclear reactions.
4. Compounds are formed when atoms of different elements combine in small whole-number ratios.

Answer 1

A) E = hν

E = energy = ?

h = Planck's constant = 6.626x10^-34 J-sec

ν = frequency and frequency = c/λ where c = speed of light (3x10⁸ m/sec) and λ = 1.00x10^-8 m (wavelength)

ν = 3x10⁸ m/sec ÷ 1x10^-8 m = 3 sec^-1

E = (6.626x10^-34 J-sec)(3 sec^-1)

E = 1.99x10^-33 J

B) Since the average mass is closest to K-39, it would be the most abundant isotope

C) 4 protons defines the element as beryllium (Be). Five neutrons gives the element an atomic mass of 4 + 5 = 9 and so the symbol for this would be ⁹₅Be

(D) Atoms can only be transformed into atoms of another element by nuclear reactions was not part of Daltons Atomic Theory