Answer for Atoms, Molecules and Stoichiometry Chemistry Exercises

1. Element : ………………….. ,

Atomic Number / number of protons / number of electrons : ………………….. ,

Neutron : ………………….. ,

Nucleon number / mass number (A) / atomic mass number  : ………………….. ,

RAM, relative atomic mass (gram per mole) : ………………….. ,

Element : Argentum / silver , Atomic Number : 47 , Neutron : 109-47 = 62, Nucleon : 109 , RAM : 196.56 g / mol,

Element : Chlorine , Atomic Number : 17 , Neutron : 37-17 = 20, Nucleon : 37 , RAM : 35.45 g / mol,

Element : Sodium / Natrium , Atomic Number : 11 , Neutron : 23-11 = 12, Nucleon : 23 , RAM : 22.98 g / mol,

Element : Fluorine , Atomic Number : 9 , Neutron : 19-9 = 10, Nucleon : 19 , RAM : 18.99 g / mol,

Element : Stannum / Tin , Atomic Number : 50 , Neutron : 120-50 = 70, Nucleon : 120 , RAM : 118.71 g / mol,

Element : Neon , Atomic Number : 10 , Neutron : 20-10 = 10, Nucleon : 20 , RAM : 20.17 g / mol,

Element :  Helium, Atomic Number : 2 , Neutron : 4-2 = 2, Nucleon : 4 , RAM : 4.0026 g / mol,

Element : Ferum / iron , Atomic Number : 26 , Neutron : 56-26 = 30, Nucleon : 56 , RAM : 55.847 g / mol,

Element : Carbon , Atomic Number : 6 , Neutron : 12-6 = 6, Nucleon : 12 , RAM : 12.0107 g / mol,

Element : Aluminium , Atomic Number : 13 , Neutron : 27-13 = 14 , Nucleon : 27 , RAM :  26.982 g / mol,

Element : Calcium , Atomic Number : 20 , Neutron : 40-20 = 20, Nucleon : 40 , RAM : 40.078 g / mol,

Element :  Manganese , Atomic Number : 25 , Neutron : 54-25 = 29, Nucleon : 54 , RAM : 54.94 g / mol,

2. We can draw a diagram of an atom by showing protons and neutrons in the nucleus surrounded by electrons.

a. Since the atomic number is 9 and the mass number is 19, the number of neutrons is 10 (19 – 9). If there are 9 protons, there must be 9 electrons.

b. Since the atomic number is 47 and the mass number is 109, the number of neutrons is 62 (109 – 47). If there are 47 protons, there must be 47 electrons.

3.

4. The subscript value refers to the atomic number (p+), and the superscript value refers to the mass number (p+ and n0).

(a) Thus, has 17 p+ and 20 n0 (37 – 17 = 20).

(b) In the periodic table, we find that the atomic number of mercury is 80.

Thus, the atomic notation, , indicates 80 p+ and 122 n0 (202 – 80 = 122).

5. (a) 50 p+ and 70 n0;

(b) 92 p+ and 146 n0

6. Answer – Click here

7. We can find the atomic mass of silicon as follows:

The average mass of a silicon atom is 28.09 amu, although we should note that there are no silicon atoms with a mass of 28.09 amu.

8. Answer, show the step work 63.55 amu

9. a. the simple average mass = 1.75g per marble

b. the weighted average mass of the marble collection = 1.75g per marble

10. The atomic number of iron is 26, and the atomic mass is 55.85 amu.

From the periodic table information, we should note that it is not possible to determine the number of isotopes for iron or their mass numbers.

11. 86 and (222)

12. atomic mass, because it contains isotopes. Answer click here Option 1, Option 2, Option 3.

13. Referring to Figure (click here), we notice that

the wavelength of yellow light is about 600 nm and

that of blue light is about 500 nm.

Thus,

(a) yellow light has a longer wavelength than blue light.

(b) blue light has a higher frequency because it has a shorter wavelength.

(c) blue light has a higher energy because it has a higher frequency.

14. The energy of light (increases/decreases) as the wavelength increases. The energy of light (increases/decreases) as the frequency increases.