---
title: Chemistry — Common Compounds
lang: en
description: Recognize common chemical compounds. Demonstrates `name-formula` (both directions), `definition`, and `basic` card types with HTML subscripts.
tags:
  - chemistry
  - compounds
  - high-school
visibility: private
---

# Chemistry — Common Compounds

> Front shows a name or a formula; back gives the matching counterpart with a short context note.
> Demonstrates the **name-formula**, **definition**, and **basic** card types.

---

## Front

H<sub>2</sub>O

## Back

**Water**

The most abundant compound on Earth's surface. Polar molecule, bent geometry (~104.5°).

<!-- card:
  cardType: name-formula
  subject: Chemistry
  topic: Inorganic compounds
  direction: formula->name
  frontType: html
  backType: markdown
  difficulty: easy
-->

---

## Front

Sodium chloride

## Back

NaCl

> info: Ionic compound; cubic crystal lattice. Dissolves in water as Na⁺ and Cl⁻ ions.

<!-- card:
  cardType: name-formula
  subject: Chemistry
  topic: Inorganic compounds
  direction: name->formula
  frontType: text
  backType: text
  difficulty: easy
-->

---

## Front

Sulfuric acid

## Back

H<sub>2</sub>SO<sub>4</sub>

> info: Strong diprotic acid. One of the most-produced industrial chemicals.

<!-- card:
  cardType: name-formula
  subject: Chemistry
  topic: Acids
  direction: name->formula
  frontType: text
  backType: html
  difficulty: medium
-->

---

## Front

What is an **ionic bond**?

## Back

A chemical bond formed by the **electrostatic attraction** between oppositely charged ions, typically a metal cation and a non-metal anion.

Characteristics:

- High melting and boiling points
- Conduct electricity when dissolved or molten
- Crystalline solids at room temperature

<!-- card:
  cardType: definition
  subject: Chemistry
  topic: Bonding
  frontType: markdown
  backType: markdown
  prompt: "Define the term and list two characteristic properties."
  difficulty: medium
-->

---

## Front

What is the **pH** scale?

## Back

A logarithmic scale (0–14) measuring the **hydrogen-ion activity** of an aqueous solution:

- pH < 7 → acidic
- pH = 7 → neutral
- pH > 7 → alkaline (basic)

A change of one pH unit corresponds to a tenfold change in $[H^+]$.

<!-- card:
  cardType: definition
  subject: Chemistry
  topic: Acid–base chemistry
  frontType: markdown
  backType: markdown
  difficulty: easy
-->

---

## Front

What does the **periodic table** organise elements by?

## Back

By **atomic number** (number of protons), arranged into rows (periods) and columns (groups).

Elements in the same group share similar chemical behaviour because they have the same number of valence electrons.

<!-- card:
  cardType: basic
  subject: Chemistry
  topic: Periodic table
  difficulty: easy
-->