Matter, Density, Atoms, Elements and Chemical Change – Flashcards (Video Notes)

A comprehensive set of practice flashcards covering matter, heat effects, density, models, atomic structure, elements, compounds, chemical changes, and the role of technology and interdisciplinary study as presented in the video notes.

How do particles move in solids, liquids, and gases according to the particle model?

Solids: closely packed and vibrate in fixed positions. Liquids: close but slide past one another. Gases: far apart and move around each other.

What happens to particle motion when heat is added or removed from matter?

Heating increases kinetic energy, speeds motion, expands, and can cause state changes; cooling decreases kinetic energy, slows motion, contracts, and can cause state changes.

In a simple particle model, what happens to particles when heat is added versus removed?

Added heat: particles gain energy and vibrate; may break apart into higher-energy states. Removed heat: particles lose energy and move closer, forming more ordered states.

What is evaporation?

The process by which a liquid changes into a gas at the surface.

What is condensation?

The process by which a gas changes into a liquid.

What is boiling?

A type of evaporation that occurs at a liquid's boiling point, where many molecules gain enough energy to become gas.

What is melting?

The process of a solid changing into a liquid.

What is freezing?

The process of a liquid changing into a solid.

How do heat energy and particle movement relate to melting, evaporation, boiling, condensation, and freezing?

Melting: solid absorbs heat; particles gain energy and move apart as a liquid. Evaporation: liquid absorbs heat; surface particles gain energy and escape as gas. Boiling: large heat input makes all molecules gain energy to become gas. Condensation: gas loses heat; particles slow and cluster into a liquid. Freezing: liquid loses heat; particles vibrate in fixed positions to form a solid.

What is density according to the particle model?

Density is a measure of how tightly packed and how heavy the molecules are in an object; the amount of matter within a certain volume.

What is the formula for density and its units?

Density = mass / volume; units: g/cm^3 or g/mL.

How do you measure the density of irregular solids?

Weigh the object for mass and measure volume using water displacement (submersion in a graduated cylinder to find the volume displaced).

What is a scientific model?

A simplified representation of a real-world system, idea, or process.

What are two benefits of using scientific models?

They provide visual representations to make abstract concepts easier to understand and enable predictions/testing of theories.

What are two limitations of scientific models?

They are overly simplified and based on assumptions; they may not fully explain concepts and can be misinterpreted.

In simple terms, how are atoms, elements, molecules, and compounds arranged?

a) Atoms: basic unit with a nucleus. b) Elements: substance of one type of atom. c) Molecules: group of two or more atoms bonded together. d) Compounds: molecules containing two or more different elements. Covalent bonds typically involve non-metals; Ionic bonds involve metals and non-metals.

What is the arrangement described for atoms in the notes?

One nucleus at the centre.

What is an element?

A substance consisting of one type of atom.

What is a molecule?

A group of two or more atoms bonded together.

What is a compound?

A substance composed of two or more different elements.

What type of elements form covalent bonds?

Non-metals (non-metal + non-metal).

What type of elements form ionic bonds?

Metals and non-metals (metal + non-metal).

What is the difference between a molecule and a compound?

A molecule is two or more atoms bonded together; a compound is a molecule that contains two or more different elements.

Give examples of common elements and molecules.

Elements: gold (Au), oxygen (O2); Molecule: water (H2O).

Give a common compound and a common mixture.

Compound: sodium chloride (NaCl). Mixture: milk (water, fats, proteins, sugars) or air (gases like N2, O2).

Why are internationally recognised symbols used for elements?

To provide a universal, concise, language-independent system that standardises chemical communication.

List the first 20 elements of the periodic table (names and symbols).

1 Hydrogen (H), 2 Helium (He), 3 Lithium (Li), 4 Beryllium (Be), 5 Boron (B), 6 Carbon (C), 7 Nitrogen (N), 8 Oxygen (O), 9 Fluorine (F), 10 Neon (Ne), 11 Sodium (Na), 12 Magnesium (Mg), 13 Aluminium (Al), 14 Silicon (Si), 15 Phosphorus (P), 16 Sulfur (S), 17 Chlorine (Cl), 18 Argon (Ar), 19 Potassium (K), 20 Calcium (Ca).

Describe the properties and uses of metals and non-metals.

Metals: lustrous, malleable, ductile, strong; good thermal/electrical conductors; uses include construction, transportation, electronics. Non-metals: often dull, brittle as solids, poor conductors; uses include life support, chemical production, agriculture.

How can you determine valency from the groups of the first 20 elements?

Valency generally corresponds to the group number for main-group elements (e.g., Group 1 = +1, Group 2 = +2, Group 17 = -1); hydrogen can have +1 or -1 depending on the compound.

Predict the formulas of simple ionic compounds: NaCl, MgCl2, NaF, AlCl3.

NaCl; MgCl2; NaF; AlCl3.

List indicators of a chemical change.

Colour change; the original substance disappears; a gas is produced (bubbles or smell); temperature changes without heating/cooling; a solid forms (precipitate); sound or light energy is released.

What does a chemical change involve?

Substances reacting to form new substances with different chemical and physical properties.

What are reactants and products?

Reactants are the substances present at the start of a reaction; products are the new substances formed.

Provide examples of chemical changes in everyday life (photosynthesis, respiration, rust).

Photosynthesis: CO2 + H2O → glucose + O2. Respiration: glucose + O2 → CO2 + H2O. Rust: Iron + oxygen + water → hydrated iron(III) oxide.

How do physical and chemical changes differ in particle arrangement and reversibility?

Physical changes: particles rearrange without changing chemical identity and are often reversible. Chemical changes: form new substances with different identities and are generally irreversible.

What has the STM (Scanning Tunnelling Microscope) taught scientists about atoms?

It allows visualization of individual atoms and the arrangement of electrons, supporting modern atomic models.

How have cultures historically used knowledge of elements and compounds?

Cultures used element properties for tools, weapons, utensils; e.g., ancient Egyptians used copper and gold for malleability and corrosion resistance.

Why should society support scientific research, e.g., in pharmaceuticals?

Leads to new medicines and vaccines, improves health/life expectancy, prepares for crises, and can drive economic growth through new industries.

How can science knowledge develop through collaboration and cross-disciplinary work?

Interdisciplinary efforts (e.g., biology, geology, oceanography) enable holistic understanding and discovery of new substances with potential applications, as shown in environments like Antarctica.