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Matter and Its Interactions Unit Introduction

Grade 8 - NC Science PS.8.1

📚 Science 🎓 Grade 8 ⏱️ 60 minutes

Learning Objectives

  • Model atomic structure including protons, neutrons, and electrons with correct locations and charges.

  • Use periodic table patterns (groups and periods) to predict basic element properties and reactivity tendencies.

  • Distinguish elements, compounds, and mixtures using particle arrangement models and separation ideas.

  • Explain chemical reactions, evidence of chemical change, and conservation of mass using models and balanced equations.

Progress 12 sections
1

Hook, essential question, vocabulary

~5 minutes

Essential Question: How do the properties of matter relate to its atomic and molecular structure? Today we build models that connect particles (atoms) to what we observe (properties and reactions).

📖 Key vocabulary

atom, proton, neutron, electron, atomic number, periodic table, chemical bond, reactant, product, conservation of mass, endothermic, exothermic

2

Atomic structure model

~12 minutes
Atomic structure model
A labeled atom model showing protons and neutrons in the nucleus and electrons in the surrounding electron cloud, with charges indicated.
A labeled atom model showing protons and neutrons in the nucleus and electrons in the surrounding electron cloud, with charges indicated.

An atom has a tiny, dense nucleus containing protons (positive) and neutrons (no charge). Electrons (negative) are found in the space around the nucleus. Atomic number identifies an element because it equals the number of protons.

3

Check your understanding A

~5 minutes
💡 Check your understanding A: Atomic structure

Answer Q-A1 through Q-A3.

Question 1

Which subatomic particle determines the atomic number of an element?

Question 2

Select all correct statements about subatomic particles.

Select all that apply.

Question 3

Why is the nucleus described as dense, even though it is very small?

Expected length: 1-2 words

4

Video anchor: periodic table overview

~4 minutes
PBS NC Science: The Periodic Table (Part 1)
5

Periodic table patterns and predictions

~10 minutes
Periodic table patterns for prediction
A simplified periodic table layout highlighting groups, periods, metals, nonmetals, and a metalloid boundary with notes on predicting properties by location.
A simplified periodic table layout highlighting groups, periods, metals, nonmetals, and a metalloid boundary with notes on predicting properties by location.

The periodic table organizes elements by atomic number. Elements in the same group often have similar properties and reactivity. Across a period, properties change gradually as atomic number increases.

6

Check your understanding B

~5 minutes
💡 Check your understanding B: Using the periodic table

Answer Q-B1 through Q-B3.

Question 4

Elements in the same group (column) on the periodic table often share:

Question 5

Use the idea of atomic number to explain why the periodic table has repeating patterns across periods (rows).

Expected length: 1-3 words

Question 6

Which general statement is most accurate?

7

Classifying matter

~8 minutes
Elements, compounds, and mixtures
Three-panel particle diagrams comparing an element, a compound, and a mixture based on atom types, bonding, and ratios.
Three-panel particle diagrams comparing an element, a compound, and a mixture based on atom types, bonding, and ratios.

An element contains one type of atom. A compound contains two or more different atoms chemically bonded in a fixed ratio. A mixture contains multiple substances together without a fixed ratio and can often be separated by physical methods.

8

Check your understanding C

~5 minutes
💡 Check your understanding C: Classifying matter

Answer Q-C1 through Q-C3.

Question 7

Which sample is a compound?

Question 8

Which are common ways to separate mixtures? (Select all that apply)

Select all that apply.

Question 9

Explain how a particle model can help you decide if a sample is a pure substance or a mixture.

Expected length: 1-3 words

9

Videos: physical vs chemical change, conservation of mass

~10 minutes
NASA STEMonstrations: Physical and Chemical Changes
NASA STEMonstrations: Conservation of Mass
10

Reaction model and conservation of mass

~7 minutes
Reaction particle model and conservation of mass
A before-and-after particle model showing the same numbers of atoms before and after a reaction, arranged into different molecules.
A before-and-after particle model showing the same numbers of atoms before and after a reaction, arranged into different molecules.

A chemical reaction rearranges atoms to form new substances (products) from starting substances (reactants). Evidence can include gas formation, precipitate, color change, and energy change. In a closed system, mass is conserved because atoms are conserved.

11

Check your understanding D

~3 minutes
💡 Check your understanding D: Reactions and conservation of mass

Answer Q-D1 and Q-D2.

Question 10

Which is the best evidence that a chemical reaction occurred?

Question 11

In an open system, why might mass appear to decrease during a reaction even if atoms are conserved?

Expected length: 1-2 words

12

Exit ticket

~3 minutes
💡 Exit ticket

Answer Q-EXIT-1 and Q-EXIT-2.

Question 12

Write a short explanation of conservation of mass using the words reactant, product, and atoms.

Expected length: 1-2 words

Question 13

An atom has 8 protons and 8 electrons. What is its net charge?