📚 Understanding Mass Number
The mass number is a crucial concept in understanding the structure of atoms. It helps us determine the number of nucleons (protons and neutrons) within an atom's nucleus.
- ⚛️ Mass number is represented by the symbol 'A'.
- 🔢 It's the total count of protons and neutrons in the nucleus.
- ➕ The formula to calculate mass number is: $A = Z + N$ where $Z$ is the atomic number (number of protons) and $N$ is the number of neutrons.
- 💡 Remember, the mass number is always a whole number.
- ⚖️ It's closely related to atomic mass, but they aren't the same. Atomic mass is a weighted average of isotopes.
- 🧪 Isotopes are atoms of the same element with differing numbers of neutrons, hence different mass numbers.
- 🌍 Examples: Carbon-12 (¹²C) has a mass number of 12, Oxygen-16 (¹⁶O) has a mass number of 16.
Practice Quiz
- What does the mass number represent?
- The number of electrons in an atom.
- The number of protons in an atom.
- The sum of protons and neutrons in an atom.
- The sum of electrons and protons in an atom.
- If an atom has 11 protons and 12 neutrons, what is its mass number?
- 1
- 11
- 12
- 23
- Which of the following is the correct formula to calculate mass number (A)?
- $A = Z - N$ (where Z is atomic number, N is number of neutrons)
- $A = Z + N$
- $A = N - Z$
- $A = Z \times N$
- What are atoms of the same element with different numbers of neutrons called?
- Ions
- Isotopes
- Molecules
- Polymers
- Carbon-14 (¹⁴C) has an atomic number of 6. How many neutrons does it have?
- 6
- 8
- 14
- 20
- What is the mass number of an alpha particle, which consists of 2 protons and 2 neutrons?
- 0
- 2
- 4
- 6
- Which of the following statements is true regarding mass number?
- Mass number can be a decimal number.
- Mass number is the same as atomic mass.
- Mass number is always a whole number.
- Mass number only considers the number of protons.
Click to see Answers
- C
- D
- B
- B
- B
- C
- C