39 articles
The Periodic Table & Elements
Groups, periods, trends and element records — how the table is organised and what it tells you.
What Is the Densest Element? Osmium, Plus the Top 10 Ranked
The densest element is osmium, at about 22.6 g/cm³, only a fraction ahead of iridium. See the top 10 densest elements with real values and why they cluster together.
The Complete List of Metals, Nonmetals, and Metalloids
Every one of the 118 elements sorted into metal, nonmetal, or metalloid, with the seven metalloids that sit right on the dividing line and why that line is fuzzy.
Periodic Table Groups and Periods: How to Read the Table
Groups are the 18 columns of the periodic table and periods are the 7 rows. Learn what each tells you about an element, plus blocks, colors and a worked example.
What Are the Largest and Smallest Atoms?
Helium is the smallest atom and cesium or francium the largest, depending on how you measure. Here's why atomic size is tricky to define, the atomic radius trend, and the numbers from our data.
The Most Expensive Elements (and Why They Cost So Much)
Which elements are the most expensive — from synthetic californium to rhodium and gold — why rarity, production difficulty and demand set the price, and why prices swing so much.
Which Element Has the Lowest Melting Point?
Helium has the lowest melting point of any element — and can't freeze at all at normal pressure. Here are the lowest melting points ranked, plus the metals that melt near room temperature.
Which Element Has the Highest Boiling Point?
Rhenium and tungsten have the highest boiling points of any element — above 5,500 °C. See the top 10 ranked from our data, why boiling points peak in the d-block, and the lowest boiling points too.
What Is the Heaviest Element? Oganesson, Uranium and Osmium
The heaviest element depends on what you mean: oganesson by atomic mass, uranium among natural elements, and osmium by density. Here's how each record-holder compares.
Which Element Has the Highest Melting Point? Carbon, Tungsten and the Top 10
The elements with the highest melting points ranked from our data — carbon, tungsten, rhenium, osmium, tantalum — why carbon's record comes with a catch, and why these metals matter.
What Is the Most Reactive Metal? The Reactivity Series Explained
Why cesium (and in theory francium) is the most reactive metal, how the alkali metals get more reactive down the group, the reactivity series, and what it predicts about displacement and extraction.
Which Elements Are Gases at Room Temperature? All 11, Explained
The 11 elements that are gases at room temperature — five diatomic gases and six noble gases — where they sit on the periodic table, why they're gases, and what each one is used for.
Which Elements Are Liquid at Room Temperature?
Only two elements — mercury and bromine — are liquid at standard room temperature. Here's why, plus the four metals that melt on a hot day and what makes each of them unusual.
What Is the Most Electronegative Element? Fluorine and the Top 10
Why fluorine is the most electronegative element, the top 10 ranked on the Pauling scale, the least electronegative elements, and what electronegativity means for bonding.
The Halogens: Fluorine, Chlorine, Bromine, Iodine and Beyond
Group 17 explained: why the halogens are so reactive, how their colour, state and reactivity change down the group, displacement reactions, and their uses from water treatment to medicine.
Element Symbols That Don't Match Their Names (and Why)
Why sodium is Na, iron is Fe, gold is Au and lead is Pb: the full list of element symbols that come from Latin, Greek and German names, with memory tips for each.
The Noble Gases: Why Group 18 Is (Almost) Unreactive
Helium, neon, argon, krypton, xenon and radon: their full electron shells, properties and trends, how they were discovered, the surprise of noble gas compounds, and their uses.
The Most Abundant Elements in the Universe (and Where They Came From)
Hydrogen and helium make up about 98% of ordinary matter. Here are the most abundant elements in the universe ranked, and how the Big Bang, stars and supernovae made them.
What Is the Best Conductor of Electricity? Silver, Copper and Gold Compared
Silver is the best electrical conductor of all the elements, but copper does most of the work. Here's why, how conductivity is measured, and where aluminium and gold fit in.
The Alkaline Earth Metals: Group 2 Properties and Uses
Beryllium, magnesium, calcium, strontium, barium and radium: their two outer electrons, trends down group 2, reactions with water, flame colours, and why calcium and magnesium matter so much.
What Is the Rarest Element on Earth?
Astatine is the rarest naturally occurring element in Earth's crust — possibly under a gram at any moment. Here's why, plus the rarest stable elements and why 'rare earths' aren't actually rare.
What Is the Hardest Element? Carbon (as Diamond) and the Hardest Metals
Carbon in the form of diamond is the hardest element. Here's how hardness is measured, why diamond is so hard, why graphite is soft, and which metals are hardest.
The Alkali Metals: Properties, Trends and Reactions of Group 1
Lithium, sodium, potassium, rubidium, cesium and francium: why they're so reactive, how their properties change down group 1, their reactions with water, and their everyday uses.
The 7 Diatomic Elements (and How to Remember Them)
The seven elements that exist as two-atom molecules — H₂, N₂, O₂, F₂, Cl₂, Br₂ and I₂ — why they pair up, the mnemonics that help you remember them, and why it matters in equations.
What Is the Lightest Element? Hydrogen and the Runners-Up
Why hydrogen is the lightest element by every measure, the lightest elements ranked by atomic mass and density, the lightest metal and solid, and why 'lightest' can mean different things.
Which Elements Are Magnetic? Ferromagnetism Explained
Only iron, cobalt, nickel and gadolinium are ferromagnetic at or near room temperature. Here's why, the difference between ferro-, para- and diamagnetism, the Curie temperature, and how rare earths make the strongest magnets.
The Carbon Group (Group 14): Carbon, Silicon, Germanium, Tin and Lead
Group 14 runs from a nonmetal to metalloids to metals. How carbon, silicon, germanium, tin and lead compare, why carbon is the basis of life and silicon of electronics, and the trend toward +2 oxidation states.
The Nitrogen Group (Group 15): Nitrogen, Phosphorus, Arsenic, Antimony and Bismuth
Group 15, the pnictogens: how nitrogen, phosphorus, arsenic, antimony and bismuth change from gas to metal, the nitrogen cycle, phosphorus in DNA and fertilizers, and arsenic's toxic history.
Electron Affinity: Definition, Trend and Why Chlorine Beats Fluorine
What electron affinity measures, the sign convention that confuses everyone, the periodic trend, why chlorine has a higher electron affinity than fluorine, and which elements don't want an extra electron.
Transition Metals: Properties, Colours and Why They Matter
What makes the d-block transition metals special: variable oxidation states, coloured compounds, catalysis and magnetism — with examples from iron, copper, chromium and titanium.
Periodic Trends Explained: The Two Ideas Behind Every Pattern
Atomic radius, ionization energy, electronegativity, electron affinity and metallic character all follow from two ideas: effective nuclear charge and shielding. Here's how, with a one-page summary.