give the number of protons, electrons and neutrons in Ca I Ag Give the number of

Question

give the number of protons, electrons and neutrons in Ca I Ag Give the number of protons and electrons in: Br^- N^3- Ba^2- Tell what is meant by the term isotopes, and; Calculate the atomic mass of copper given that the metal has 2 naturally occurring isotopes; copper-63 (69.17%, isotopic mass = 62.94 amu) and copper-65 (30.85 %; isotopic mass = 64.93 amu). Calculate: The number atoms of potassium in a 5.36 g sample of the metal The number of O_2 molecules in a 4.00g sample of the gas. The mass of 6.032 Times 10^22 atoms of Cu

Explanation / Answer

3. a)

(i) Ca -

Number of protons - 20

Number of electrons - 20

Number of neutrons - 20

(ii) I

Number of protons - 53

Number of electrons - 53

Number of neutrons - 74

(iii) Ag

Number of protons - 47

Number of electrons - 47

Number of neutrons - 60

3. b)

(i) Br-

Number of protons - 35

Number of electrons - 36

Number of neutrons - 45

(ii) N3-

Number of protons - 7

Number of electrons - 10

Number of neutrons - 7

(iii) Ba2+

Number of protons - 56

Number of electrons - 54

Number of neutrons - 81

4. a)

Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties are isotopes.

b)

5. a)

To determine the number of atoms in 5.36 gm, it's a simple conversion.

Start with the mass (g), get the number of moles by dividing by the atomic mass (g/mol), and then the number of atoms by avogadro's number (6.02x1023 atoms/mol).

So.. (5.36 g) / (39 g/mol) x (6.02x1023 atoms/mol) = 8.27 x1022.

5. b)

To determine the number of atoms in 4.00 gm,

Start with the mass (g), get the number of moles by dividing by the atomic mass (g/mol), and then the number of atoms by avogadro's number (6.02x1023 atoms/mol).

So.. (4.00 g) / (32 g/mol) x (6.02x1023 atoms/mol) = 7.525 x1022.

c). 6.02x1023 atoms of Cu = 1 mole of Cu = 63.55 g

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