Chemistery

When two atoms share electrons in a bond, the sharing is rarely fair. One atom almost always pulls harder than the other. Electronegativity is the number that captures that pull — and it quietly decides whether a bond turns out ionic, polar, or perfectly even. The short answer: electronegativity is a measure of how strongly an atom attracts the shared electrons in a chemical bond. The higher an atom's electronegativity, the harder it tugs the bonding electrons toward itself. What electronegativity actually measures Picture a chemical bond as a tug-of-war over a pair of electrons. Electronegativity tells you how strong each atom is in that contest. A highly electronegative atom (like fluorine or oxygen) pulls the shared electrons close. A weakly electronegative atom (like sodium) barely pulls at all and tends to lose the electrons outright. Chemists put this on a scale called the Pauling scale , running from about 0.7 up to 3.98: Fluorine (F) = 3.98 — the most electronega...

You've met ions — atoms with a charge. They come in exactly two flavours: cations and anions . The names sound almost identical, which is exactly why students mix them up on exams. Let's lock in the difference for good. The short answer: a cation is a positively charged ion (an atom that lost electrons). An anion is a negatively charged ion (an atom that gained electrons). Cation = positive, anion = negative. Quick comparison at a glance Feature Cation Anion Charge Positive (+) Negative (−) How it forms Loses electrons Gains electrons Protons vs electrons More protons than electrons More electrons than protons Usually formed by Metals (+ NH₄⁺, H⁺) Nonmetals Size vs the original atom Smaller than the atom Larger than the atom Moves toward (in electrolysis) The cathode (−) The anode (+) Examples Na⁺, Mg²⁺, Ca²⁺, NH₄⁺ Cl⁻, O²⁻, OH⁻, SO₄²⁻ Everything below is just these rows explained — including a couple of tricks so you ...

A sodium atom is a soft metal that explodes in water. A sodium ion is half of ordinary table salt — completely harmless. Same element, one tiny change. That change is what makes an ion , and it's behind salts, batteries, and the signals firing in your nerves right now. The short answer: an ion is an atom (or group of atoms) that has gained or lost one or more electrons , giving it an overall electric charge. Lose electrons → positive ion. Gain electrons → negative ion. What an ion actually is Remember that a neutral atom has equal numbers of protons (+) and electrons (−), so the charges cancel. An ion forms when that balance is broken — but only the electrons move. The protons never change. That last point matters: because the proton count stays the same, it's still the same element . A sodium ion is still sodium; it has just lost an electron and picked up a charge. Lose electrons → fewer negatives than positives → a positive ion (a cation ). Gain electrons → more...

Look at a periodic table and most of it is metals — but the small patch of nonmetals on the right side includes oxygen, carbon, and nitrogen, the elements life is made of. Telling the two groups apart is one of the first skills that makes the periodic table feel readable. The short answer: metals tend to be shiny, conduct electricity, bend without breaking, and lose electrons. Nonmetals tend to be dull, don't conduct, are brittle when solid, and gain or share electrons. On the periodic table, a zig-zag staircase line separates the metals (left and centre) from the nonmetals (upper right). Quick comparison at a glance Feature Metals Nonmetals Position on the table Left and centre (most of it) Upper right Appearance Shiny (lustrous) Dull Electrical/heat conductivity Good conductors Poor (insulators) When solid Malleable & ductile (bend, stretch) Brittle (shatter) State at room temperature Mostly solid (mercury is liquid) Gases, liquids, or ...

If electrons all look the same, why do chemists obsess over just a handful of them? Because only the outermost ones — the valence electrons — actually do the chemistry. Learn to spot them and you can predict how almost any element will behave. The short answer: a valence electron is an electron in an atom's outermost shell (its highest energy level). These outer electrons are the ones that take part in forming bonds, so they control how an element reacts. What valence electrons actually are Electrons sit in shells around the nucleus, filling from the inside out. For the first 20 elements you can use a simple capacity rule: 1st shell: holds up to 2 electrons 2nd shell: holds up to 8 3rd shell: holds up to 8 (at this level) Whatever electrons end up in the last occupied shell are the valence electrons. The inner electrons are tucked away and shielded; they don't get involved in everyday bonding. The outer ones are exposed — they're what one atom "sees...

Two numbers sit next to almost every element symbol, and they trip up a lot of students: the atomic number and the mass number . They look similar, they're both whole numbers, and mixing them up quietly wrecks a lot of otherwise-correct answers. The short answer: the atomic number is the number of protons in an atom (it defines the element). The mass number is the total number of protons + neutrons in the nucleus. One identifies which element; the other tells you how heavy that particular atom is. Quick comparison at a glance Feature Atomic number (Z) Mass number (A) What it counts Protons only Protons + neutrons Symbol Z A What it tells you Which element it is The mass of that specific atom Same for every atom of an element? Yes — always No — can vary (isotopes) On the periodic table? Yes (the whole number for each element) Not directly (the table shows average atomic mass) In a neutral atom, also equals Number of electrons — Th...