Uvero — STEM Learning

Mechanism

Follow the mechanism step by step and distinguish what causes the change from what is merely observed.

This extension applies that lens specifically to Elements and Compounds.

Pure substances come in two kinds:

An element is made of only one type of atom and cannot be broken into simpler substances by chemical means. Copper ( $\text{Cu}$ ), oxygen ( $\text{O}_2$ ) and carbon ( $\text{C}$ ) are elements. The periodic table is the list of all known elements.
A compound is two or more elements chemically bonded in a fixed ratio. Water ( $\text{H}_2\text{O}$ ) is always two hydrogen atoms to one oxygen. Table salt is sodium chloride ( $\text{NaCl}$ ).

A compound's properties are usually nothing like the elements that formed it. Sodium is a metal that reacts violently with water; chlorine is a poisonous green gas — yet bonded together they make the salt on your chips.

Chemistry — Grade 10 — Mechanism: Which substance is a compound?

$\text{Cu}$ (copper)

$\text{O}_2$ (oxygen gas)

$\text{CO}_2$ (carbon dioxide)

$\text{Fe}$ (iron)

Chemistry — Grade 10 — Mechanism: In water, $\text{H}_2\text{O}$ , the ratio of hydrogen atoms to oxygen atoms is always…

1 : 1

2 : 1

1 : 2

any ratio you like

Chemistry — Grade 10 — Mechanism: Is $\text{O}_2$ (oxygen gas) an element or a compound? Answer with one word.

Name the original topic being extended by this mechanism lesson.

Which statement is the best evidence-led starting point for Elements and Compounds: Mechanism?

Pure substances come in two kinds: - An element is made of only one type of atom and cannot be broken into simpler substances by chemical means. Copper ( $\text{Cu}$ ), oxygen ( $\text{O}_2$ ) and carbon ( $\text{C}$ ) are elements. The periodic table is the list of all known elements. - A compound is two or more elements chemically bonded in a **f

Pure Substances and Mixtures

Separating Mixtures

A conclusion needs no observations, calculations or stated assumptions.