What is the symbol, atomic number, and group of Hydrogen? — Symbol: H · Atomic number: 1 · Group: 1 · Period: 1. Lightest element. Most abundant in the universe. Forms water (H₂O) and acids. Diatomic gas (H₂).

What is the symbol, atomic number, and group of Helium? — Symbol: He · Atomic number: 2 · Group: 18 (Noble gas). Lightest noble gas. Used in balloons and MRI machines. Completely unreactive.

What is the symbol, atomic number, and group of Lithium? — Symbol: Li · Atomic number: 3 · Group: 1 (Alkali metal). Softest metal, stored in oil (reacts with water). Used in batteries and psychiatric medications.

What is the symbol, atomic number, and group of Carbon? — Symbol: C · Atomic number: 6 · Group: 14. Basis of all organic life. Forms diamond (hardest natural substance) and graphite. 4 valence electrons — forms 4 bonds.

What is the symbol, atomic number, and group of Nitrogen? — Symbol: N · Atomic number: 7 · Group: 15. Makes up 78% of Earth's atmosphere. Diatomic (N₂) with a triple bond. Found in amino acids, proteins, and DNA.

What is the symbol, atomic number, and group of Oxygen? — Symbol: O · Atomic number: 8 · Group: 16. Makes up 21% of Earth's atmosphere. Essential for cellular respiration. Highly electronegative. Diatomic (O₂).

What is the symbol, atomic number, and group of Fluorine? — Symbol: F · Atomic number: 9 · Group: 17 (Halogen). Most electronegative element on the periodic table. Most reactive nonmetal. Forms HF (hydrofluoric acid).

What is the symbol, atomic number, and group of Neon? — Symbol: Ne · Atomic number: 10 · Group: 18 (Noble gas). Colorless, odorless, unreactive gas. Used in neon signs (glows red-orange).

What is the symbol, atomic number, and group of Sodium? — Symbol: Na · Atomic number: 11 · Group: 1 (Alkali metal). Soft, silvery metal. Reacts vigorously with water. Found in table salt (NaCl). Essential electrolyte in the body.

What is the symbol, atomic number, and group of Magnesium? — Symbol: Mg · Atomic number: 12 · Group: 2 (Alkaline earth metal). Burns with brilliant white light. Used in alloys, fireworks, and chlorophyll.

What is the symbol, atomic number, and group of Aluminum? — Symbol: Al · Atomic number: 13 · Group: 13. Most abundant metal in Earth's crust. Lightweight, corrosion-resistant. Used in aircraft, cans, and foil.

What is the symbol, atomic number, and group of Silicon? — Symbol: Si · Atomic number: 14 · Group: 14 (Metalloid). Second most abundant element in Earth's crust. Basis of computer chips and semiconductors. Found in sand (SiO₂).

What is the symbol, atomic number, and group of Phosphorus? — Symbol: P · Atomic number: 15 · Group: 15. Essential in DNA, ATP, and cell membranes. White phosphorus is highly toxic and flammable. Found in fertilizers.

What is the symbol, atomic number, and group of Sulfur? — Symbol: S · Atomic number: 16 · Group: 16. Yellow solid with distinctive smell when burned (sulfur dioxide). Used in sulfuric acid (H₂SO₄) — most produced industrial chemical.

What is the symbol, atomic number, and group of Chlorine? — Symbol: Cl · Atomic number: 17 · Group: 17 (Halogen). Toxic yellow-green gas. Diatomic (Cl₂). Used to disinfect water and in PVC plastic. Forms NaCl (table salt).

What is the symbol, atomic number, and group of Argon? — Symbol: Ar · Atomic number: 18 · Group: 18 (Noble gas). Third most abundant gas in atmosphere (~1%). Used in welding to prevent oxidation. Completely unreactive.

What is the symbol, atomic number, and group of Potassium? — Symbol: K · Atomic number: 19 · Group: 1 (Alkali metal). Symbol from Latin Kalium. Reacts explosively with water. Essential electrolyte for nerve and muscle function.

What is the symbol, atomic number, and group of Calcium? — Symbol: Ca · Atomic number: 20 · Group: 2 (Alkaline earth metal). Most abundant mineral in the human body. Found in bones, teeth, chalk (CaCO₃), and limestone.

What is the symbol, atomic number, and group of Iron? — Symbol: Fe · Atomic number: 26 · Group: 8 (Transition metal). Symbol from Latin Ferrum. Most used metal in the world. Core component of steel. Carries oxygen in hemoglobin.

What is the symbol, atomic number, and group of Copper? — Symbol: Cu · Atomic number: 29 · Group: 11 (Transition metal). Symbol from Latin Cuprum. Excellent electrical conductor. Used in wiring and plumbing. Forms blue-green patina (verdigris).

What is the symbol, atomic number, and group of Zinc? — Symbol: Zn · Atomic number: 30 · Group: 12 (Transition metal). Used to galvanize steel (prevent rust). Essential trace element in the human diet. Found in batteries.

What is the symbol, atomic number, and group of Silver? — Symbol: Ag · Atomic number: 47 · Group: 11 (Transition metal). Symbol from Latin Argentum. Best electrical conductor of all metals. Used in jewelry, photography, and antibacterials.

What is the symbol, atomic number, and group of Gold? — Symbol: Au · Atomic number: 79 · Group: 11 (Transition metal). Symbol from Latin Aurum. Extremely unreactive — resists corrosion. Used in electronics, jewelry, and currency.

What is the symbol, atomic number, and group of Mercury? — Symbol: Hg · Atomic number: 80 · Group: 12 (Transition metal). Symbol from Latin Hydrargyrum. Only metal that is liquid at room temperature. Highly toxic. Used in thermometers (historically).

What is the symbol, atomic number, and group of Lead? — Symbol: Pb · Atomic number: 82 · Group: 14. Symbol from Latin Plumbum (origin of "plumbing"). Dense, soft metal. Used in batteries. Highly toxic — causes neurological damage.

What is electronegativity and which element has the highest? — Electronegativity is the tendency of an atom to attract bonding electrons toward itself. Fluorine has the highest electronegativity (4.0 on Pauling scale). Increases across a period (left→right) and up a group.

What is ionization energy and how does it trend on the periodic table? — Energy required to remove an electron from a gaseous atom. Increases left to right across a period and increases bottom to top up a group. Noble gases have the highest ionization energies.

What is atomic radius and how does it trend on the periodic table? — The size of an atom (distance from nucleus to outermost electron). Decreases left to right (more protons pull electrons closer). Increases top to bottom (more electron shells added).

What are the alkali metals and their key property? — Group 1 elements: Li, Na, K, Rb, Cs, Fr. All have 1 valence electron — highly reactive, especially with water. Reactivity increases down the group. Stored in oil to prevent reaction with air/water.

What are the halogens and their key property? — Group 17 elements: F, Cl, Br, I, At. All have 7 valence electrons — need 1 more to complete their outer shell, making them highly reactive nonmetals. Form salts when reacting with metals.

What are noble gases and why are they unreactive? — Group 18 elements: He, Ne, Ar, Kr, Xe, Rn. They have a complete outer electron shell (8 electrons, or 2 for helium) — no tendency to gain, lose, or share electrons.

What are transition metals and where are they on the periodic table? — Elements in groups 3–12, filling the d-block. They have variable oxidation states, form colored compounds, are good conductors, and are often used as catalysts. Examples: Fe, Cu, Zn, Au, Ag.

What is the difference between a period and a group on the periodic table? — A period is a horizontal row — elements in the same period have the same number of electron shells. A group (column) contains elements with the same number of valence electrons and similar chemical properties.

What is Avogadro's number and what is a mole? — Avogadro's number = 6.022 × 10²³. A mole is the amount of substance containing this many particles (atoms, molecules, ions). It links atomic mass (in amu) to grams.

What is the Aufbau principle? — Electrons fill orbitals starting from the lowest energy level to the highest. The order is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p... Each orbital holds maximum 2 electrons.