Question

explain how to find the # of neutrons atomic mass protons
3
li
6.941
atomic # =
atomic mass =

of protons =

of neutrons =

of electrons =

14
silicon
28.086
atomic # =
atomic mass =

of protons =

of neutrons =

of electrons =

Explanation:

For Lithium (Li):

Step1: Recall Atomic Number

Atomic number (Z) is the number of protons, and for Li, the atomic number is 3 (from the top left, which is the atomic number). So Atomic # = 3.

Step2: Recall Atomic Mass

Atomic mass is the bottom number, so Atomic Mass = 6.941 (we can round it to 7 for neutron calculation as neutrons are calculated from mass number, which is the rounded atomic mass).

Step3: Number of Protons

In a neutral atom, number of protons = atomic number, so # of Protons = 3.

Step4: Number of Neutrons

Neutrons (n) = Mass number (A) - Atomic number (Z). Mass number A is the rounded atomic mass, so A = 7, Z = 3. Thus, n = 7 - 3 = 4. So # of Neutrons = 4.

Step5: Number of Electrons

In a neutral atom, number of electrons = number of protons, so # of Electrons = 3.

For Silicon (Si):

Step1: Recall Atomic Number

The atomic number of silicon is 14 (from the top left, atomic number). So Atomic # = 14.

Step2: Recall Atomic Mass

Atomic mass is 28.086 (bottom number), so Atomic Mass = 28.086 (we can take mass number A = 28 as it's the rounded atomic mass).

Step3: Number of Protons

Number of protons = atomic number, so # of Protons = 14.

Step4: Number of Neutrons

Neutrons (n) = A - Z. A = 28, Z = 14. So n = 28 - 14 = 14. Thus, # of Neutrons = 14.

Step5: Number of Electrons

In a neutral atom, electrons = protons, so # of Electrons = 14.

Answer:

(for each part):

Lithium:

Atomic # = 3
Atomic Mass = 6.941

of Protons = 3

of Neutrons = 4

of Electrons = 3

Silicon:

Atomic # = 14
Atomic Mass = 28.086

of Protons = 14

of Neutrons = 14

of Electrons = 14