Question

discovering the nucleus:
in ____ model of the atom, electrons travel around the nucleus like around the sun. rutherford experimented using ____ and alpha particles.

mass number:
when describing the structure of an atom, most of the mass comes from the protons and the neutrons. electrons have almost no mass (.0005). the total number of the ____ + ____ in an atom is called the mass number.

check for understanding:
count the number of protons & neutrons to get the atomic number and mass number. put the corresponding values next to the carbon symbol: c.

isotopes: all atoms of an element have the same number of protons. however, atoms of the same element may have different numbers of ____. isotopes are atoms that have the same number of protons but different numbers of neutrons. since isotopes of an element have ____ numbers of neutrons, they also have different mass numbers.

Explanation:

Discovering the Nucleus:

In the Rutherford (or planetary) model of the atom, electrons travel around the nucleus like planets around the sun. Rutherford experimented using gold foil and alpha particles. (The diagram likely has labels for nucleus, electrons, etc.—common labels here would be "Nucleus", "Electrons", and the model name is Rutherford’s planetary model.)

Mass Number:

When describing the structure of an atom, most of the mass comes from the protons and the neutrons. Electrons have almost no mass (≈0.005). The total number of the $\boldsymbol{\text{protons}}$ + $\boldsymbol{\text{neutrons}}$ in an atom is called the mass number.

Isotopes:

All atoms of an element have the same number of protons. However, atoms of the same element may have different numbers of $\boldsymbol{\text{neutrons}}$. Isotopes are atoms that have the same number of protons but different numbers of neutrons. Since isotopes of an element have $\boldsymbol{\text{different}}$ numbers of neutrons, they also have different mass numbers.

Check for Understanding (Carbon, C):

• Atomic number (protons): Carbon has 6 protons (atomic number = 6).
• Neutrons: For the most common isotope (C-12), neutrons = mass number – protons = 12 – 6 = 6.
• So, atomic number = 6, mass number = 12 (for C-12; other isotopes like C-13 have mass number 13, neutrons = 7, etc.).

Filling in Blanks (Summarized Answers):

1. Discovering the Nucleus:

• Model: Rutherford (planetary)
• Experiment material: gold foil
• Diagram labels (if needed): Nucleus, Electrons, etc.

1. Mass Number:

• Blanks: $\boldsymbol{\text{protons}}$ + $\boldsymbol{\text{neutrons}}$

1. Isotopes:

• First blank: $\boldsymbol{\text{neutrons}}$
• Second blank: $\boldsymbol{\text{different}}$

1. Carbon (C):

• Atomic number (protons): 6
• Mass number (e.g., for C-12): 12
• Neutrons (for C-12): 6

Answer:

Discovering the Nucleus:

In the Rutherford (or planetary) model of the atom, electrons travel around the nucleus like planets around the sun. Rutherford experimented using gold foil and alpha particles. (The diagram likely has labels for nucleus, electrons, etc.—common labels here would be "Nucleus", "Electrons", and the model name is Rutherford’s planetary model.)

Mass Number:

When describing the structure of an atom, most of the mass comes from the protons and the neutrons. Electrons have almost no mass (≈0.005). The total number of the $\boldsymbol{\text{protons}}$ + $\boldsymbol{\text{neutrons}}$ in an atom is called the mass number.

Isotopes:

All atoms of an element have the same number of protons. However, atoms of the same element may have different numbers of $\boldsymbol{\text{neutrons}}$. Isotopes are atoms that have the same number of protons but different numbers of neutrons. Since isotopes of an element have $\boldsymbol{\text{different}}$ numbers of neutrons, they also have different mass numbers.

Check for Understanding (Carbon, C):

• Atomic number (protons): Carbon has 6 protons (atomic number = 6).
• Neutrons: For the most common isotope (C-12), neutrons = mass number – protons = 12 – 6 = 6.
• So, atomic number = 6, mass number = 12 (for C-12; other isotopes like C-13 have mass number 13, neutrons = 7, etc.).

Filling in Blanks (Summarized Answers):

1. Discovering the Nucleus:

• Model: Rutherford (planetary)
• Experiment material: gold foil
• Diagram labels (if needed): Nucleus, Electrons, etc.

1. Mass Number:

• Blanks: $\boldsymbol{\text{protons}}$ + $\boldsymbol{\text{neutrons}}$

1. Isotopes:

• First blank: $\boldsymbol{\text{neutrons}}$
• Second blank: $\boldsymbol{\text{different}}$

1. Carbon (C):

• Atomic number (protons): 6
• Mass number (e.g., for C-12): 12
• Neutrons (for C-12): 6