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Unizon
Chemistry Path · Lens 2: Science

The Science
of Chemistry

The opening question
Why does salt dissolve in water but oil doesn’t, and how could Mendeleev predict elements nobody had found?

Look inside the atom, learn to read the periodic table, see how atoms bond into salts, molecules and metals, spot chemical reactions, and test acids and bases safely with a red-cabbage indicator.

Inside this module
  • 00First Principlesp.2
  • 01Inside the atomp.4
  • 02The periodic tablep.5
  • 03Bondingp.6
  • 04Reactionsp.7
  • 05Acids & basesp.8
  • ✦Self-check · Make it · 5 Questions · Side Questp.9
How this works
CoreThe main path. Everyone does this part.
Level UpOptional, harder challenges if you want to push further.
Try ItMake a red-cabbage rainbow.

You'll need: a notebook, red cabbage, clear cups, kitchen ingredients, eye protection and an adult.

Chemistry Path · Unizon01/12
Chemistry Path · Unizon · Lens 2: Science00 · Start here
Before anything else
First
Principles

A first principle is a basic truth you can build on. The science of chemistry rests on four: everything is made of atoms, an element is set by its number of protons, electrons decide how atoms bond and reactions rearrange atoms into new substances.

1

What do I already know?

Dump it all out. Half-sure counts.
What do you think is inside an atom?
What’s the difference between melting ice and burning wood?
Circle every word you could explain to a friend right now. Underline the ones you've heard but couldn't explain.
protonneutronelectronnucleusatomic numberisotopeperiodgroupioncovalent bondreactionindicator
2

What is necessary?

The building blocks you need before going further

Everything in this module is built from four bricks. Rate yourself on each one, then check the example to see if your rating holds up.

AtomsEverything. matter
Got itKindaNot yet
ProtonsSet the element. Z
Got itKindaNot yet
ElectronsMake bonds. share/give
Got itKindaNot yet
ReactionsRearrange. new stuff
Got itKindaNot yet
Is anything else necessary? What else do you think you'd need to know or have to really get this topic?
The Science of Chemistry · Chemistry Path · Unizon02/12
Chemistry Path · Unizon · Lens 2: Science00 · Start here
3

What is the objective?

What am I trying to understand or be able to do by the end?
The module's objective

By the end, you’ll be able to describe the parts of an atom, read the periodic table, explain ionic, covalent and metallic bonds, recognize chemical reactions, and test acids and bases safely.

  • 01Name the 3 parts of an atom.
  • 02Find an element’s group and period.
  • 03Tell ionic from covalent bonds.
  • 04Spot 4 signs of a reaction.
  • 05Explain pH and indicators.
  • 06Explain neutralization.
My objective

The list on the left is ours. Now make it yours. What do you want out of this?

By the end, I want to be able to
The part I'm most curious about is
I'll know I've got there when
Knowledge meter

How much do you know about the science of chemistry right now? Shade the boxes in pencil. You'll come back at the end (p.9) and shade it again in pen.

NothingCould teach it

Why start this way? When you know what you already have (1), what you need (2) and where you're going (3), you learn faster and you notice the gaps. Every module on the Chemistry Path starts with these same three questions.

Your route through this module
00
First Principles
01
Atoms
02
Table
03
Bonds
04
Reactions
05
pH
✓
Check
▶
Make
?
5 Qs
★
Quest
The Science of Chemistry · Chemistry Path · Unizon03/12
Chemistry Path · Unizon · Lens 2: Science01 · Atoms
01
Tiny and mostly empty

Inside the atom

Protons, neutrons and electrons build every atom.

Inside the atom

Three particles

ParticleChargeWhere
Proton+1Nucleus
Neutron0Nucleus
Electron−1Around the nucleus

The number of protons is the atomic number. Every carbon atom has 6.

Isotopes

Same element, different mass

  • Atoms of one element can have different numbers of neutrons.
  • Carbon-12 has 6 neutrons; carbon-14 has 8.
  • Mass number = protons + neutrons.
  • A neutral atom has as many electrons as protons.
Mostly empty

A stadium and a pea

The nucleus is about 1/100,000 of the atom’s width. If an atom were a hockey arena, the nucleus would be about the size of a pea at centre ice, holding almost all the mass.

Think & talk
  • Why do you think atoms are mostly empty space, yet things feel solid?
  • What would you ask an atom if it could answer?
Try it

Count the parts

Oxygen has atomic number 8 and mass number 16. How many protons, neutrons and electrons does a neutral atom have?
Level Up

Sodium-23 (atomic number 11) has how many neutrons?

23 − 11 = 12
The Science of Chemistry · Chemistry Path · Unizon04/12
Chemistry Path · Unizon · Lens 2: Science02 · Table
02
A map of the elements

The periodic table

The periodic table groups elements that act alike.

Reading the table

Rows and columns

  • 118 elements are known, ordered by atomic number.
  • Periods (rows) show how many electron shells an atom uses.
  • Groups (columns 1–18) share similar properties.
  • Metals sit on the left and centre; nonmetals on the right.

11Nasodium
22.9917Clchlorine
35.452Hehelium
4.003

Families

Groups behave alike

  • Group 1 (alkali metals): soft, very reactive with water.
  • Group 17 (halogens): reactive nonmetals like chlorine.
  • Group 18 (noble gases): helium, neon, argon; very unreactive.
  • Elements in a group have the same number of outer electrons.
Did you know?

Gaps that came true

In 1869 Dmitri Mendeleev left gaps for elements nobody had found and predicted their properties. Gallium (1875) and germanium (1886) fit his predictions closely (see Lens 5).

Think & talk
  • Why was leaving gaps in the table such a bold idea?
  • Which element would you most like to see in real life?
Try it

Find it

Use a periodic table (a free one online or in a textbook) to find the group and period of calcium, iron and iodine.
Level Up

Why do helium and neon both resist reacting?

Same group: full outer electron shells
The Science of Chemistry · Chemistry Path · Unizon05/12
Chemistry Path · Unizon · Lens 2: Science03 · Bonds
03
Holding atoms together

Bonding

How electrons behave decides how atoms join.

Three ways to bond

Give, share or pool

  • Ionic: a metal gives electrons to a nonmetal. Sodium becomes Na+, chlorine becomes Cl−, and they attract: table salt.
  • Covalent: nonmetals share pairs of electrons, as in water, H2O.
  • Metallic: metal atoms share a “sea” of electrons, so metals conduct.
Why water is special

A bent, polar molecule

Water’s oxygen pulls shared electrons harder than its hydrogens, so one end is slightly negative and the other slightly positive. That polarity lets water pull salt ions apart.

Oil molecules aren’t polar, so oil and water don’t mix.

Like dissolves like

A useful rule

Polar substances (salt, sugar) tend to dissolve in polar water. Nonpolar ones (oil, wax) dissolve in nonpolar liquids. Dish soap has one end of each kind, which is how it lifts grease.

Think & talk
  • Why might salt dissolve in water but oil not?
  • Where do you see metals, salts and molecules in your home?
Try it

Dissolve test

In 3 clear cups of room-temperature water, stir in a spoon of salt, sugar and cooking oil. What happens in each? Which are mixtures that stay mixed?
Level Up

Why do metals conduct electricity?

Their electrons can move freely
The Science of Chemistry · Chemistry Path · Unizon06/12
Chemistry Path · Unizon · Lens 2: Science04 · Reactions
04
Something new

Reactions

In a chemical reaction, new substances form.

Signs of a reaction

New substances form

  • A gas forms (bubbles you didn’t add).
  • A colour change.
  • A temperature change: hotter (exothermic) or colder (endothermic).
  • A solid forms in a liquid (a precipitate).
  • Light or a new smell.
Physical vs chemical

Same stuff or new stuff?

ChangeType
Ice meltingPhysical
Sugar dissolvingPhysical
Toast browningChemical
Iron rustingChemical

Physical changes are usually easy to reverse; chemical ones usually aren’t.

Feel the cold

Baking soda and vinegar

This reaction is slightly endothermic: the cup gets a little cooler as CO2 bubbles off. Hand warmers do the opposite, releasing heat as iron reacts with oxygen.

Think & talk
  • How can you tell a chemical change from a physical one?
  • Which reaction in your kitchen surprises you most?
Try it

Sort them

Classify as physical or chemical: boiling water, frying an egg, bread rising, breaking glass, milk going sour, salt dissolving.
Level Up

Is a burning candle only a physical change?

No: wax melts (physical) and burns (chemical)
The Science of Chemistry · Chemistry Path · Unizon07/12
Chemistry Path · Unizon · Lens 2: Science05 · pH
05
Sour and slippery

Acids & bases

Acids and bases cancel each other out.

Acids and bases

Opposites on the pH scale

  • Acids (pH below 7) taste sour: lemon juice, vinegar.
  • Bases (pH above 7) feel slippery: soap, baking soda in water.
  • Strong acids and bases burn skin and eyes.

Never taste or touch to test. Use an indicator.

Neutralization

Acid + base → salt + water

HCl + NaOH → NaCl + H2O

Antacid tablets are mild bases that neutralize extra stomach acid. Baking soda fizzing with vinegar is also an acid meeting a base.

Indicators

Colour that reports pH

Red cabbage contains pigments called anthocyanins. They turn red or pink in acids, purple near neutral, and blue or green in bases. Some flowers and berries work the same way.

Think & talk
  • Why should strong acids and bases stay out of home experiments?
  • Where do acids and bases help you every day?
Try it

Predict colours

Predict the colour red-cabbage juice will turn in vinegar, plain water and baking-soda water. Test them in the mini-challenge.
Level Up

What two products does an acid and a base usually make?

A salt and water
The Science of Chemistry · Chemistry Path · Unizon08/12
Chemistry Path · Unizon · Lens 2: ScienceSelf-check
✓
No pressure, just proof

Quick self-check

Six questions, covering every stop. Show your thinking. Answers are upside down at the bottom; no peeking till you're done.

1 · What charge does a proton have?

2 · What does the atomic number tell you?

3 · What is a group on the periodic table?

4 · How is an ionic bond different from a covalent bond?

5 · Name 3 signs of a chemical reaction.

6 · What colour does red-cabbage juice turn in an acid?

1) +1 · 2) the number of protons · 3) a column of elements with similar properties · 4) ionic: electrons given; covalent: electrons shared · 5) e.g. gas, colour change, temperature change · 6) red or pink
Back to First Principles

Re-shade your knowledge meter

How much do you know about the science of chemistry now? Flip back to p.3 and shade the meter again in pen (or shade this one). Did any of the four bricks on p.2 move from "Not yet" to "Got it"?

NothingCould teach it
Did I hit my objective? What's my evidence?
The idea that surprised me most:
The Science of Chemistry · Chemistry Path · Unizon09/12
Chemistry Path · Unizon · Lens 2: ScienceMini challenge · Make it
Mini challenge · Execution

Red-cabbage rainbow

Use a natural indicator to sort acids and bases.

1 · Plan

An adult chops a quarter of a red cabbage and pours hot water over it. Let it cool, strain it, then add a spoonful of the purple juice to small cups of each test liquid.

  • Adult handles knife and hot water
  • Eye protection on
  • Cups labelled
  • Kitchen liquids only

2 · Results

LiquidColourAcid or base?
Vinegar
Lemon juice
Water
Baking-soda water
Milk

3 · Must-haves

  • Predictions first
  • Colours recorded
  • Order from acid to base
  • Clean-up done

4 · What I found

What happens if you add vinegar to the blue baking-soda cup?

Safety first

Kitchen liquids only. Never test bleach, drain or oven cleaner, ammonia or toilet cleaner: they can burn skin and eyes, and some make toxic gases when mixed. Don’t drink the test cups.

The Science of Chemistry · Chemistry Path · Unizon10/12
Chemistry Path · Unizon · Lens 2: Science5 Questions I Still Have
The best part of learning is what's next

5 Questions
I Still Have

This module didn't answer everything. Good. Write 5 new questions it didn't answer, one of each type below. There are no wrong questions, only ones nobody's asked yet.

1
How does it work?
Pick something you've seen or used and wonder about the inside of. e.g. "Will scientists find element 119?"
2
Why?
Ask about a reason or a cause. e.g. "Why are some isotopes radioactive?"
3
What if?
Change one thing and imagine the result. e.g. "What if water weren’t polar?"
4
Connect it
Link this to another lens (math, science, psychology, technology, history, language & storytelling, art & design, execution) or another subject. e.g. "Why do certain smells feel so strong? (Lens 3!)"
5
My life & community
Bring it home: your family, your friends, your community. e.g. "How do indicators change colour?"

★ Star the one question you'd most like answered. You'll need it on the next page.

The Science of Chemistry · Chemistry Path · Unizon11/12
Chemistry Path · Unizon · Lens 2: ScienceSide Quest · Optional
Optional · for the curious

Side Quest

Take your starred question from p.11 and go find the answer, or at least a better question. You're the researcher now.

My quest question:

1What I'll find out

Break your big question into 2 or 3 smaller ones you could actually answer.

2Where I'll look

A library (Edmonton Public Library counts!)An astronomer, engineer or planetarium guideAn experiment I run myselfTrustworthy websites (who wrote it? when?)A book or documentary

3How I'll share it

A one-page zineA 60-second video or talkA poster or infographicA 2-minute talkSomething else

Who I'll share it with:

Done by:

Next on the Chemistry Path Lens 3 · Psychology asks: how do chemicals shape feelings, taste and smell, and why do people fear “chemicals”?
The Science of Chemistry · Chemistry Path · Unizon12/12