Chemistry 8 Lesson 4: Atoms
1. Summary of theory
1.1. What is atom?
Atoms are extremely small, electrically neutral particles.
+ 1 nucleus has a positive charge.
A shell made up of one or more negatively charged electrons.
The total positive charge of the nucleus is equal to the total negative charge of the electrons.
The nucleus of an atom is made up of protons and neutrons.
– Symbol: p
– Charge: +1
– Weight: 1.6726.10-24g
b. Neutron Particles
– Symbol: n
– Charge: no charge.
– Weight: 1.6726.10-24g
In each atom: Number p = number e
1.3. Electron Layer
– In an atom, electrons move very quickly around the nucleus and are arranged in layers, each layer has a certain number of electrons.
Number of electron shells of an atom:
+ FRIENDS2 : 1 (1e) → the outermost 1e .
+ O2 : 2 (8e) → the outermost 6e.
+ Na: 3 (11e) → the outermost 1e.
– Maximum number of e in class 1: 2e
– Maximum number of e in class 2: 8e
2. Illustrated exercise
2.1. Form 1: Comment on the relative mass between the particles p, n, e
Read the information below to complete table 1.2 on page 20.
Atoms are extremely small particles. Scientists have done many experiments to show that atoms are made of smaller particles, called subatomic particles.
If we imagine the Sun as the nucleus of an atom, the planets would be electrons moving around the nucleus.
Complete Table 1.2 and based on that comment on the relative masses of protons, neutrons, and electrons.
– Protons and neutrons have the same mass, while electrons have a very small, insignificant mass (only about 0.0005 times the mass of a proton). So nuclear mass is considered as atomic mass.
– Atoms of the same type have the same number of protons in their nucleus.
In an atom, the number of protons is equal to the number of electrons: Number p = Number e.
2.2. Form 2: Determine the atomic structure
The figure below shows the structure of 6 atoms from A to F .
a) Indicate which atoms are of the same type.
b) Calculate the total number of particles of the above atoms.
a) A and F are atoms of the same type because they have the same number of protons, 5
D and E are atoms of the same type because they have the same number of protons, 16 .
b) Atoms are electrically neutral, so the number of protons is equal to the number of electrons
Total number of particles of an atom = number of protons + number of neutrons + number of electrons
A: 5 + 6 + 5 = 16
B: 6 + 6 + 6 = 18
C: 15 + 16 + 15 = 46
D: 16 + 16 + 16 = 48
E: 16 + 17 + 16 = 49
F: 5 + 5 + 5 = 15
2.3. Form 3: Complete the data table
Fill in the blanks in the following table:
Let the number of protons, neutrons and electrons in an atom be: P, N, E . respectively
For atom A:
For atom B:
EREMOVE = 8 PREMOVE = 8 and WOMENREMOVE = 8 ⇒ (Total number of seeds)REMOVE = PREMOVE + FEMALEREMOVE + EREMOVE = 24
For the C atom:
For atom D:
PEASY = 19 and PEASY = EEASY
⇒ EEASY = 19
PEASY + WOMENEASY + EEASY = 58 ⇒ 19 + WOMENEASY + 19 = 58 ⇒ WOMENEASY = 20
Fill in the data in the table as follows:
3.1. Essay exercises
Question 1: Fill in the blanks with the missing words
“Atoms are extremely small particles and … electrically. An atom consists of a positively charged nucleus and a shell made of … bearing …”
Verse 2: Give the number of p, number of e, number of layers e and number of outermost layer e of (I)
Question 3: Atoms have the ability to bond with each other. Why?
Verse 4: Fill in the blanks
“In nature, hydrogen has a twin brother…. Atom…. also known as ‘hydrogen…’, only differing by 1….”
Question 5: What is in the space between the nucleus and the electron shell of an atom?
3.2. Multiple choice exercises
Question 1: Choose the best answer
A. Number of p=number of e
B. Nuclei made of protons and electrons
C. Electrons do not move around the nucleus
D. Electron arranged in layers
Verse 2: Choose the wrong answer
A. The mass of the nucleus is considered to be the mass of the atom
B. Number of p = number of e
C. The nucleus is made up of protons and neutrons
D. Oxygen has a different number of p than e
Question 3: The diameter of the atom is
A. 10-8 cm
B. 10-9 cm
C. 10-8 m
Verse 4: Why is the mass of an atom equal to the mass of the nucleus? Choose the correct answer
A. Since protons and neutrons have the same mass, electrons have very little mass
B. Since number p = number e
C. Because the nucleus is made up of protons and neutrons
D. Because neutrons don’t carry electricity
Question 5: The kernel is made up of:
A. Neutrons and electrons
B. Protons and electrons
C. Protons and neutrons
After the lesson to be understood: Determine the number of nuclear charge units, p number, e number, number of e layers, number of e in each layer based on the atomic structure diagram of a few specific elements (H, C, Cl, Na).