Chemistry Olympiad Olympiad Science — practice questions
22 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice Chemistry Olympiad Olympiad Science in the app →An atom is stable when its valence shell holds a full set of electrons called an:To reach that stable arrangement, atoms may lose, gain or:Two hydrogen atoms joining together form a molecule of an:Hydrogen and chlorine atoms joining together form a molecule of a:Noble gases exist as single atoms because their atoms are already:The force that holds two bonded atoms together is called a chemical:A bond formed when two atoms share a pair of electrons is called:A shared electron pair makes the molecule stable because it attracts both:A hydrogen atom has one electron, so to become stable it needs one:Each chlorine atom in a chlorine molecule needs to gain a share of electrons numbering:In an oxygen molecule the two atoms share two pairs, which makes a bond that is:In a water molecule, hydrogen completes not an octet but a:An atom with more than four valence electrons will usually gain or share to complete its:An atom with only one or two valence electrons will generally instead:A sodium atom that loses its single valence electron becomes a positively charged:A chlorine atom that gains an electron becomes a negatively charged:Sodium and chloride ions are then held together by a force that is:A bond formed by that transfer and attraction is called:Ionic compounds are built as three-dimensional structures called:In sodium chloride, the number of chloride ions surrounding each sodium ion is:The repeating pattern of ions in such a solid is represented as a crystal:The chemical formula of common salt, used as the standard ionic example, is: