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Digestive System Disorders: Causes, Symptoms, Treatment & Prevention Guide

Disorders of the Digestive System - Causes, Symptoms & Treatment Disorders of the Digestive System: Causes, Symptoms, Treatment & Prevention 1. Introduction to Digestive Disorders The digestive system breaks down food and absorbs nutrients. Disorders like acid reflux, IBS, or ulcers can interfere with these processes. Understanding symptoms, causes, and treatments is essential for maintaining gut health. 2. Common Digestive System Disorders Acid Reflux (GERD): Stomach acid flows into the esophagus causing heartburn. Peptic Ulcers: Open sores in the stomach or small intestine. Irritable Bowel Syndrome (IBS): Affects bowel habits with cramping and bloating. Constipation: Infrequent or painful bowel movements. Diarrhea: Loose, frequent stools. Inflammatory Bowel Disease (IBD): Includes Crohn's disease and ulcerative colitis. Gallstones: Block bile flow, causing pain an...
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Atomic Number and Mass Number – Definition, Explanation, Examples, and MCQs

 Atomic Number and Mass Number

Atomic Number (Z)

Definition:

The atomic number of an element is the number of protons present in the nucleus of its atom. It is represented by the symbol Z.

Explanation:

  • Every atom is made up of protons, neutrons, and electrons.
  • The number of protons in an atom is always fixed for a particular element.
  • It determines the identity of an element.
  • Since atoms are neutral, the number of electrons is also equal to the atomic number.

Examples:

  • Hydrogen (H): Atomic number = 1 (1 proton, 1 electron)
  • Carbon (C): Atomic number = 6 (6 protons, 6 electrons)
  • Oxygen (O): Atomic number = 8 (8 protons, 8 electrons)

Key Points:

  • Atomic number increases as we move across the periodic table.
  • It helps in arranging elements in the periodic table.

Mass Number (A)

Definition:

The mass number of an atom is the total number of protons and neutrons present in its nucleus. It is represented by the symbol A.

Formula:


Mass Number (A) = Number of Protons (Z) + Number of Neutrons (N)

Explanation:

  • Electrons have negligible mass, so the mass of an atom mainly comes from protons and neutrons.
  • The number of neutrons can vary, even in the same element, leading to isotopes.

Examples:

  • Carbon-12 (C-12):
    • Protons = 6
    • Neutrons = 6
    • Mass Number = 6 + 6 = 12
  • Oxygen-16 (O-16):
    • Protons = 8
    • Neutrons = 8
    • Mass Number = 8 + 8 = 16

Key Points:

  • Mass number is not found on the periodic table because it can vary due to isotopes.
  • It helps in calculating the number of neutrons.

Summary:

  • Atomic Number (Z) = Number of protons (always fixed for an element).
  • Mass Number (A) = Protons + Neutrons (can change due to isotopes).
  • Atomic number determines element identity, while mass number tells about the mass of the atom.

Solved Example 1:

An atom has 11 protons and 12 neutrons. Find its atomic number and mass number.

Solution:

We know that:

  • Atomic Number (Z) = Number of Protons

Z = 11


A = 11 + 12 = 23

Answer:

  • Atomic Number (Z) = 11
  • Mass Number (A) = 23

Since the atomic number is 11, the element is Sodium (Na).

Solved Example 2:

An element has a mass number of 40 and an atomic number of 20. Find the number of protons, neutrons, and electrons.

Solution:

We are given:

  • Mass Number (A) = 40
  • Atomic Number (Z) = 20

We know that:

  • Number of Protons = Atomic Number

Protons= 20


Electrons= 20


Neutrons = 40 - 20 = 20

Answer:

  • Protons = 20
  • Electrons = 20
  • Neutrons = 20

Since the atomic number is 20, the element is Calcium (Ca).

Multiple Choice Questions (MCQs)

  1. The atomic number of an element is the number of:
    a) Neutrons
    b) Protons
    c) Electrons
    d) Both protons and neutrons
    (Answer: b)

  2. The mass number of an atom is the sum of:
    a) Protons and electrons
    b) Protons and neutrons
    c) Neutrons and electrons
    d) None of these
    (Answer: b)

  3. The atomic number of oxygen is:
    a) 6
    b) 7
    c) 8
    d) 9
    (Answer: c)

  4. Which subatomic particle determines the identity of an element?
    a) Neutron
    b) Proton
    c) Electron
    d) None of these
    (Answer: b)

  5. If an element has 12 protons, what is its atomic number?
    a) 10
    b) 11
    c) 12
    d) 13
    (Answer: c)

  6. The mass number of an atom with 9 protons and 10 neutrons is:
    a) 9
    b) 10
    c) 18
    d) 19
    (Answer: d)

  7. The number of neutrons in carbon-14 (C-14) is:
    a) 6
    b) 7
    c) 8
    d) 14
    (Answer: c)

  8. Which element has an atomic number of 1?
    a) Oxygen
    b) Hydrogen
    c) Helium
    d) Nitrogen
    (Answer: b)

  9. The mass number is represented by the symbol:
    a) A
    b) Z
    c) N
    d) M
    (Answer: a)

  10. The atomic number of chlorine (Cl) is:
    a) 16
    b) 17
    c) 18
    d) 19
    (Answer: b)

  11. What is the atomic number of helium (He)?
    a) 1
    b) 2
    c) 3
    d) 4
    (Answer: b)

  12. The mass number of an atom depends on the number of:
    a) Protons only
    b) Neutrons only
    c) Protons and neutrons
    d) Electrons
    (Answer: c)

  13. If an atom has 15 protons and 16 neutrons, its mass number is:
    a) 15
    b) 16
    c) 31
    d) 32
    (Answer: c)

  14. Which particle does NOT contribute to the mass number of an atom?
    a) Proton
    b) Neutron
    c) Electron
    d) None of these
    (Answer: c)

  15. The atomic number of an element is always:
    a) Equal to the number of protons
    b) Equal to the number of neutrons
    c) Equal to the number of electrons and neutrons
    d) Different from the number of protons
    (Answer: a)

  16. The number of neutrons in uranium-238 (U-238) is:
    a) 92
    b) 146
    c) 238
    d) 146
    (Answer: b)

  17. Which of the following has an atomic number of 3?
    a) Lithium
    b) Beryllium
    c) Boron
    d) Carbon
    (Answer: a)

  18. If an element has 20 protons and 22 neutrons, its mass number is:
    a) 20
    b) 22
    c) 40
    d) 42
    (Answer: c)

  19. The atomic number of an element increases when:
    a) A proton is added
    b) A neutron is added
    c) An electron is added
    d) An electron is removed
    (Answer: a)

  20. If an atom has 7 protons, its element is:
    a) Carbon
    b) Nitrogen
    c) Oxygen
    d) Fluorine
    (Answer: b)

Short Questions

  1. Define atomic number.
  2. Define mass number.
  3. What is the atomic number of hydrogen?
  4. How is mass number calculated?
  5. Which subatomic particles contribute to the mass number?
  6. Why does atomic number determine the identity of an element?
  7. What is the mass number of an atom with 7 protons and 8 neutrons?
  8. What is the difference between atomic number and mass number?
  9. If an atom has 15 protons and 16 neutrons, what is its atomic number?
  10. Can two elements have the same atomic number? Why or why not?
  11. What is the atomic number of oxygen?
  12. How do electrons affect the atomic number?
  13. Why is the number of protons equal to the number of electrons in a neutral atom?
  14. Give an example of an isotope and its mass number.
  15. How can you calculate the number of neutrons in an atom?
  16. What is the atomic number of carbon?
  17. If an atom has a mass number of 40 and 20 protons, how many neutrons does it have?
  18. What is the mass number of chlorine-37?
  19. What is the difference between isotopes and elements?
  20. Why do isotopes have the same atomic number but different mass numbers?
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