Grade: 8 Subject: Science Unit: Physical Science Lesson: 3 of 6 SAT: Information+Ideas ACT: Science

Guided Practice

Learn

In this guided practice lesson, you will apply your knowledge of atomic structure and the periodic table to solve problems step by step. We will work through examples together, building your confidence in physical science concepts.

Key Concepts Review

  • Atoms consist of protons, neutrons, and electrons
  • The atomic number identifies an element
  • Periodic table organization reflects element properties
  • Electron configuration determines chemical behavior

Examples

Work through these examples to see the concepts in action.

Example 1: Identifying Subatomic Particles

An atom has 6 protons and 6 neutrons. Identify the element and its mass number.

Solution: The element is carbon (C) because it has 6 protons. Mass number = 6 + 6 = 12.

Example 2: Reading the Periodic Table

Find the element with atomic number 11 and describe its properties.

Solution: Sodium (Na) - an alkali metal, highly reactive, one valence electron.

✏️ Practice

Test your understanding with these practice questions.

Practice Questions

0/3 correct
Question 1

What is the scientific method's first step?

A Conduct experiment
B Make a hypothesis
C Ask a question
D Draw conclusions
Explanation: The scientific method begins with asking a question about something you observe.
Question 2

A hypothesis is:

A A proven fact
B A testable prediction
C The final answer
D An observation
Explanation: A hypothesis is an educated guess or testable prediction that can be investigated.
Question 3

Which is a property of matter?

A Color
B Speed
C Direction
D Time
Explanation: Properties of matter include color, mass, volume, density, and texture.

Check Your Understanding

Test yourself with these 10 quiz questions.

Question 1: What determines an element's identity?

Answer: The number of protons (atomic number) determines an element's identity.

Question 2: How many protons does an atom of nitrogen have?

Answer: 7 protons (atomic number of nitrogen is 7).

Question 3: What is the mass number of an atom with 8 protons and 8 neutrons?

Answer: 16 (mass number = protons + neutrons = 8 + 8 = 16).

Question 4: Which subatomic particle has a negative charge?

Answer: The electron has a negative charge.

Question 5: What do elements in the same period have in common?

Answer: Elements in the same period have the same number of electron shells (energy levels).

Question 6: Why are noble gases unreactive?

Answer: Noble gases have a full outer electron shell, making them stable and unreactive.

Question 7: What is an isotope?

Answer: An isotope is a version of an element with the same number of protons but a different number of neutrons.

Question 8: How many valence electrons does carbon have?

Answer: Carbon has 4 valence electrons.

Question 9: Where are metals located on the periodic table?

Answer: Metals are located on the left side and center of the periodic table.

Question 10: What is the atomic mass unit (amu) based on?

Answer: The atomic mass unit is based on 1/12 the mass of a carbon-12 atom.

Next Steps

  • Review any concepts that felt challenging
  • Move on to the Lab Analysis lesson
  • Return to practice problems periodically for review