Units / Unit A / Periodic Table Patterns and Combining Ratios

Periodic Table Patterns and Combining Ratios

Use the periodic table to explain how and why elements combine in specific ratios (A-GO2-SO3, SO4).

Full lesson guide (printable)

Outcome checklist

Alberta Program of Studies — tick each row when you can explain it without the slide.

A-GO2-SO3
By the end of this lesson you should be able to: Explain, using the periodic table, how and why elements combine to form compounds in specific ratios
Self-check: Without looking at your notes, give one example or explanation that shows you meet A-GO2-SO3.
A-GO2-SO4
By the end of this lesson you should be able to: Predict formulas and write names for ionic and molecular compounds and common acids (e.g., sulfuric, hydrochloric, nitric, ethanoic), using a periodic table, a table of ions and IUPAC rules
Self-check: Without looking at your notes, give one example or explanation that shows you meet A-GO2-SO4.
A-GO2
Big idea: Explain, using the periodic table, how elements combine to form compounds, and follow IUPAC guidelines for naming ionic compounds and simple molecular compounds
Self-check: How does today's lesson connect to A-GO2?

Where this shows up later

Unit A — Naming compounds: Formulas follow from ionic and molecular bonding.
Unit A — Acids and bases: Ionic and molecular behaviour includes acids.

Glossary

group: Key vocabulary for this lesson (group). Use your class notes and the slide explanations to state it in your own words — Alberta Science 10 expects you to use this term correctly in context.
period: Key vocabulary for this lesson (period). Use your class notes and the slide explanations to state it in your own words — Alberta Science 10 expects you to use this term correctly in context.
valence: Key vocabulary for this lesson (valence). Use your class notes and the slide explanations to state it in your own words — Alberta Science 10 expects you to use this term correctly in context.
ion: Key vocabulary for this lesson (ion). Use your class notes and the slide explanations to state it in your own words — Alberta Science 10 expects you to use this term correctly in context.
ionic bond: Attraction between oppositely charged ions after electron transfer.
covalent bond: Electrons shared between atoms in a molecule.

Lab and demo watch-outs

Classroom safety
Follow school rules for equipment, goggles, and fire safety even during thought experiments.
Any time hands-on work is suggested.

Slide 1 of 813%

Hook

Why does sodium chloride always have the same formula?

NaCl — not NaCl2 or Na2Cl5.
Pattern must come from atomic structure.

Core explanation

We start with a real situation: NaCl — not NaCl2 or Na2Cl5. Pattern must come from atomic structure. Your job is to notice evidence and ask questions before memorizing definitions.

Check your understanding

Can you connect this slide to something we learned earlier today?

Explain moreDeeper teaching notes — read like a tutor explaining the idea

Unit A — Periodic Table Patterns and Combining Ratios: Patterns on the periodic table predict how atoms bond and form compounds. On this slide («Why does sodium chloride always have the same formula?»), the science story is: NaCl — not NaCl2 or Na2Cl5. Pattern must come from atomic structure. Read like a tutor: connect each bullet to evidence or a model, not memorized wording. Alberta Science 10 expects you to explain ideas in class discussions and written work — this slide supports outcomes A-GO2-SO3, A-GO2-SO4.

Worked example(s)Step-by-step reasoning, not just answers

Apply: Why does sodium chloride always have the same formula?
1. State the core idea: NaCl — not NaCl2 or Na2Cl5.
2. Link to a second point: Pattern must come from atomic structure.
3. Give one Alberta or daily-life example that fits both ideas.
4. Check your example against the slide — would your teacher agree?
Why this works: Application proves understanding beyond repeating bullets.

Common mistakes to avoid

Students may think group number always equals valence for all groups without transition metals context.
On «Why does sodium chloride always have the same formula?», use the slide model and vocabulary (group, period, valence, ion) to replace this idea.

Try it yourself

Teach «Why does sodium chloride always have the same formula?» aloud in 60 seconds using two bullets and one vocabulary word from group.