Kerala SSLC Chemistry flashcards
Kerala SSLC Chemistry · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Mole
- The amount of substance containing 6.022 × 10^23 particles (Avogadro number). One mole of any substance has a mass in grams equal to its molar mass.
- Avogadro number
- The number of particles (atoms, molecules, ions) in one mole of a substance, equal to 6.022 × 10^23 per mole. Used to convert particle counts to moles.
- Molar volume at STP
- The volume occupied by one mole of any gas at standard temperature and pressure (0 °C, 1 atm), equal to 22.4 litres. Used to convert gas volume to moles.
- Molar mass
- The mass of one mole of a substance in grams per mole, numerically equal to its formula mass in atomic mass units. Obtained by adding atomic masses of all atoms in the formula.
- Empirical formula
- The formula showing the simplest whole-number ratio of atoms of each element in a compound. For example, hydrogen peroxide has empirical formula HO and molecular formula H2O2.
- Molecular formula
- The formula showing the actual number of atoms of each element in one molecule. It equals the empirical formula multiplied by a whole number n.
- Atomic number
- The number of protons in the nucleus of an atom, denoted Z. It determines the element's identity and its position in the modern periodic table.
- Mass number
- The sum of protons and neutrons in an atom's nucleus, denoted A. Neutrons = mass number minus atomic number.
- Isotopes
- Atoms of the same element with the same atomic number but different mass numbers because they have different numbers of neutrons. They show identical chemical properties.
- Valence electrons
- Electrons in the outermost shell of an atom. They determine the group of the element and control chemical reactivity and bonding behaviour.
- Electronic configuration
- The arrangement of electrons in shells around the nucleus, written as 2, 8, 8, 2 for the first twenty elements. The outermost shell configuration decides valency.
- Balanced chemical equation
- An equation in which the number of atoms of each element is equal on both sides, achieved by adjusting coefficients only. It obeys the law of conservation of mass.
- Law of conservation of mass
- In a chemical reaction, matter is neither created nor destroyed, so total mass of reactants equals total mass of products. This justifies balancing equations.
- Percentage composition
- The mass of a particular element in a compound expressed as a percentage of the compound's total molar mass. Calculated as element mass per mole divided by molar mass times 100.
- Relative molecular mass
- The sum of the atomic masses of all atoms present in one molecule of a substance, expressed in atomic mass units. Numerically equal to molar mass in g/mol.
- Cation
- A positively charged ion formed when an atom loses one or more electrons. Metals such as sodium and magnesium form cations readily.
- Anion
- A negatively charged ion formed when an atom gains one or more electrons. Non-metals such as chlorine and oxygen form anions.
- Ionic bond
- The electrostatic force of attraction between oppositely charged ions formed by transfer of electrons from a metal to a non-metal. Ionic compounds are crystalline and conduct when molten.
- Covalent bond
- A bond formed by the sharing of one or more pairs of electrons between atoms, usually non-metals. Shared pairs may be single, double or triple.
- Electrovalency
- The number of electrons lost or gained by an atom to form an ion, equal to the magnitude of charge on the ion. Sodium shows electrovalency one; oxygen shows two.
- Covalency
- The number of electron pairs an atom shares with other atoms in forming covalent bonds. Carbon commonly shows a covalency of four.
- Acid
- A substance that releases hydrogen ions (H+) in aqueous solution, turns blue litmus red, and reacts with bases to form salt and water.
- Base
- A substance that releases hydroxide ions (OH-) in aqueous solution, turns red litmus blue, and neutralises acids to give salt and water.
- Neutralisation
- The reaction between an acid and a base producing salt and water. For example, hydrochloric acid plus sodium hydroxide gives sodium chloride and water.
- pH scale
- A scale from 0 to 14 measuring hydrogen ion concentration: below 7 acidic, 7 neutral, above 7 basic. Each unit change means a tenfold change in H+ concentration.
- Salt
- A compound formed when the hydrogen of an acid is replaced by a metal or ammonium ion during neutralisation. Salts are usually crystalline solids.
- Oxidation
- A process involving loss of electrons or gain of oxygen or loss of hydrogen by a substance. The oxidised species increases its oxidation number.
- Reduction
- A process involving gain of electrons or loss of oxygen or gain of hydrogen by a substance. The reduced species decreases its oxidation number.
- Redox reaction
- A reaction in which oxidation and reduction occur simultaneously. The substance oxidised is the reducing agent; the substance reduced is the oxidising agent.
- Oxidising agent
- A substance that accepts electrons and thereby oxidises another substance while being reduced itself. Examples include oxygen, chlorine and potassium permanganate.
- Reducing agent
- A substance that donates electrons and thereby reduces another substance while being oxidised itself. Examples include hydrogen, carbon and sodium.
- Periodic table period
- A horizontal row of the modern periodic table whose elements have the same number of electron shells. Elements are arranged in order of increasing atomic number.