Chemistry: Elements, Compounds, Reactions, and the Periodic Table

Comprehensive practice flashcards covering basic chemistry notes including elements, states of matter, separation methods, atomic structure, the periodic table, Mendeleev's developments, chemical compounds, experimental accuracy, and Group 1, Group 7, and Group 0 chemical trends.

Element

An element is made up of atoms of the same type. These are found in the periodic table.

Diffusion

The movement of particles from an area of high concentration to an area of low concentration.

The Law of Conservation of Mass

Mass cannot be created or destroyed, only rearranged, meaning the total mass of the reactants always equals the total mass of the products.

Filtration

A separation method that uses filter paper and a funnel to separate an undissolved solid from a liquid.

Distillation

A physical separation process used to separate two liquids (such as Ribena and water) by boiling and condensation, where the liquid with the lower boiling point distils away while the other remains behind.

Crystallisation

A separation technique where a solution (such as salt dissolved in water) is heated to evaporate the liquid, leaving solid crystals behind.

Chromatography

A technique used to separate mixtures of soluble substances, such as coloured inks, using chromatography paper and a pencil line.

State Symbols

Standard chemical abbreviations used to indicate physical states: $(s)$ for solid, $(l)$ for liquid, and $(g)$ for gas.

Periodic Table

A structured table that displays all known elements, organized into metals on the left and non-metals on the right.

Staircase Line

The dividing stepped line on the periodic table that separates the metals on the left from the non-metals on the right.

Abundance of Metals vs. Non-Metals

Metals are significantly more abundant on the periodic table than non-metals, with approximately $5$ times more metals than non-metals.

Scientific Model

A visual representation used to make difficult scientific ideas easier to visualise and understand, although it is not accurate in scale regarding size and distance.

Proton

A subatomic particle located in the nucleus with a relative mass of $1$ and a positive charge of $+1$.

Neutron

A subatomic particle found in the nucleus with a relative mass of $1$ and a neutral charge of $0$.

Electron

A negatively charged subatomic particle with a charge of $-1$ and a relative mass of $\frac{1}{2000}$, found in shells or orbits surrounding the nucleus ($2000$ electrons equal the mass of $1$ proton or neutron).

Electronic Configuration

The specific arrangement of electrons within the shells, orbits, or energy levels surrounding an atom's nucleus.

Atomic Number

The bottom number of an element entry representing the number of protons in the nucleus, which also equals the number of electrons in a neutral atom.

Relative Atomic Mass

The top number of an element entry representing the total mass of the nucleus, calculated as the sum of protons and neutrons.

Physical Property

A characteristic describing how a substance behaves without undergoing chemical alteration, where changes in state or appearance are easily reversible.

Chemical Property

A characteristic describing how a substance interacts and reacts with other materials based on its atomic structure, such as wood combusting into ash.

Malleable

A property describing a material that can be hammered, bent, or pressed into various shapes without shattering.

Ductile

A property describing a material that can be easily pulled or stretched into thin wires without breaking.

Sonorous

A property describing a material that produces a ringing sound when struck.

Physical Properties of Metals

Common characteristics shared by metals, including high density, high melting and boiling points, and good conductivity of both heat and electricity.

Physical Properties of Non-Metals

Common characteristics shared by non-metals, including low density, low melting and boiling points, being dull in appearance, brittle, and poor conductors of heat and electricity.

Sterling Silver

An alloy composed of $92.5\%$ silver and $7.5\%$ copper, created because pure silver is too weak and easily broken for functional jewellery.

Bronze

A sonorous metal alloy commonly used to make bells because it rings clearly when struck and resists outdoor weathering.

Mendeleev's Gaps

Intentional blank spaces left in Dmitri Mendeleev's periodic table for undiscovered elements, allowing him to predict their missing physical properties with high accuracy.

Mendeleev's Periodic Organisation

A three-stage classification system grouping elements with similar properties together and ordering them by increasing atomic weight both from left to right and from top to bottom.

Compound

Compounds are made of two or more different types of atoms, chemically bonded together, and they have different properties

Sodium Chloride Formation

A vigorous chemical reaction between reactive, shiny silvery sodium metal and poisonous green chlorine gas, producing flame, bright white light, and white crystals of edible salt ($2\text{Na} + \text{Cl}_2 \rightarrow 2\text{NaCl}$).

Iron Sulfide

A non-magnetic black powder compound formed from chemically combining magnetic grey iron and low-density yellow sulfur powder.

The '-ate' Naming Rule

A chemical nomenclature convention indicating that a compound contains three components: a metal, a non-metal, and oxygen (such as calcium nitrate, sodium sulfate, or potassium carbonate).

Valence Electron Trends by Group

A periodic pattern where the group number dictates outer shell electrons: Group 1 has $1$ ($+1$ charge), Group 2 has $2$, Group 3 has $3$, Group 5 has $5$ ($3$ gaps, $-3$ charge), Group 6 has $6$ ($2$ gaps, $-2$ charge), Group 7 has $7$ ($1$ gap, $-1$ charge), and Group 0/8 has $8$ (full shell, $0$ gaps).

Repeatable

Experimental results achieved when the same scientist uses the same apparatus in the same laboratory and obtains similar outcomes.

Reproducible

Experimental results achieved when a different scientist uses different equipment in a different location (such as London vs. Wakefield) and obtains similar outcomes.

Accuracy

How close a measured experimental value is to the true, known, or accepted target value.

Precision

How close repeated experimental measurements are to each other, regardless of whether they hit the true target.

Open System

An experimental setup where matter or energy can enter or leave, which may falsely make it appear that the law of conservation of mass was not obeyed (such as gas escaping).

Closed System

An experimental setup where matter and energy are completely prevented from entering or escaping (such as sealing a conical flask with a rubber stopper), keeping total measured mass unchanged.

Group 1 Physical Trends

Moving down the alkali metals, hardness decreases from $0.6$ to $0.2$ (getting softer), melting points decrease from $181^\circ\text{C}$ (lithium) to $28^\circ\text{C}$ (caesium), boiling points decrease from $1342^\circ\text{C}$ to $671^\circ\text{C}$, and density generally increases from $0.53\,\text{g/cm}^3$ to $1.87\,\text{g/cm}^3$ (except potassium at $0.89\,\text{g/cm}^3$).

Alkali Metal Reactions with Water

Group 1 metals react vigorously with water to form an alkaline metal hydroxide solution and hydrogen gas ($\text{Metal} + \text{Water} \rightarrow \text{Metal Hydroxide} + \text{Hydrogen}$).

Alkali Metal Reactions with Oxygen

Group 1 metals react with oxygen gas to yield metal oxides, forming compounds with formulas such as $\text{K}_2\text{O}$, $\text{Rb}_2\text{O}$, $\text{Cs}_2\text{O}$, and $\text{Fr}_2\text{O}$.

Group 7 Halogen Trends

Moving down Group 7, the halogens become progressively darker in colour, and their melting and boiling points steadily increase (melting points rise from $-220^\circ\text{C}$ to $+114^\circ\text{C}$, and boiling points rise from $-188^\circ\text{C}$ to $+183^\circ\text{C}$).

Fluorine

The most reactive Group 7 halogen, existing as a very pale yellow gas with a melting point of $-220^\circ\text{C}$ and a boiling point of $-188^\circ\text{C}$.

Chlorine

A Group 7 halogen that exists as a pale green gas with a melting point of $-100^\circ\text{C}$ and a boiling point of $-35^\circ\text{C}$.

Bromine

A Group 7 halogen that exists as a red/brown liquid with a melting point of $-7^\circ\text{C}$ and a boiling point of $+58^\circ\text{C}$.

Iodine

A Group 7 halogen that exists as a dark grey solid with a melting point of $+114^\circ\text{C}$ and a boiling point of $+183^\circ\text{C}$.

Group 0 Noble Gases

A family of colourless, odourless, and tasteless non-metals with completely full outer electron shells, making them chemically unreactive and stable.

Helium Balloon Application

Helium is used safely to float balloons because its density is lower than air and its full outer shell makes it stable, whereas hydrogen is no longer used due to being flammable and explosive.

Reactivity Mechanism of Group 1 Metals

Group 1 metals are highly reactive because they readily lose their single valence electron to expose an underlying full, stable outer shell of $8$ electrons.

Reactivity Mechanism of Group 7 Non-Metals

Group 7 non-metals are highly reactive because they readily gain one electron to complete their valence shell with a stable octet of $8$ electrons.