chemistry flashcards

Atom: The smallest unit of an element that retains the properties of that element.

Element: A pure substance made up of one type of atom only.

Compound: A substance that is made up of 2+ atoms chemically bonded in a fixed ratio and cannot be physically separated.

Mixture: A group of molecules physically combined

Molecule: The smallest structural unit of an element/compound that retains the properties of that element or compound.

Electrons: A negatively charged subatomic particle, 1 ATM found in electron cloud in electron shells/energy levels.

Protons: A positively charged subatomic particle, 1 ATM found in the nucleus

Neutrons: A neutrally charged subatomic particle, 1/1800 ATM found in in the nucleus

Atomic number: Tells the order of elements and tells the number of protons in the nucleus. and the numbers of electrons in a balanced atom.

Atomic mass: The number of protons and neutrons.

Electron configuration: The arrangement of electron in shells; 2, 8, 8.

Valence electrons: The outermost electrons.

Ions:  Charged particles (indicated in superscript) that have gained or lost electrons, to gain a full outer shell, and hence become stable. If they gained electrons, they are negatively charged, and if they lost electrons they are positively charged.

Isotopes: Have more neutrons than a regular element (different version) and have different atomic masses.

Valency: The ability of an atom to lose or gain electrons.

Valency charge: The amount of electrons that need to be gained/lost to have a complete outer shell. (- charge = electrons need to be lost, + charge = electrons need to be gained).

Group: Columns on a periodic table that determine the number of valence electrons (group number).

Period: Rows on a periodic table that determine the number of electron shells (period number).

Ionic compound:  A combination of atoms where electron(s) are exchanged between a metal and a non-metal.

Anion: A negatively charged ion, usually a non-metal.

Cation: A positively charged ion, usually a metal.

Covalent compound: A combination of atoms where the bond between them is pair(s) of shared electrons coming from each of the atoms in the bond, hence stability.

Atomic weight: Total weight, protons + neutrons, calculated using weighted averages.

Law of conservation: Matter cannot be destroyed or created, moved around.

Limiting reagent: Reactant, entirely used, consumed first, less atomic weight.

Moles: Standard scientific unit of 6.022x10^23 elementary entities (e.g. atoms or molecules).

Molar mass: Atomic mass x no. of atom.

Stoichiometry: Using relationships in a chemical reaction to determine desired quantitative data.

Chemical change: Bubbling due to creation + temp changes + colour changes + new substance formed.

Physical change: Change in state in matter + size + shape + no new substances.

Metal acid reaction: Metal + acid → salt + hydrogen.

Metal displacement: More reactive metal, more solutions to displace, displaced metal precipitates out of solution.

Metal activity series: Reactivity decreases when it goes down the series, metals above hydrogen + acid → hydrogen gas.

Activity series applications: Extracts precious metals, coats cheap metals with precious metals, galvanises (prevents oxidation).

Ionisation energy: Amount of energy, specific atom, lose an electron (kJ mol-1), 1st ionisation energy.

Ionisation energy → electronegativity: Higher ionisation energy → higher electronegativity.

Electronegativity: Tendency to attract electrons, affected by atomic number and distance.

Atomic number in electronegativity: Higher the atomic number, more electrons → electron shells → more distance.

Distance in electronegativity: More distance → more reactivity → gravitational attraction not as strong.

Atomic structure: Periodic table.

Ionic structure: Group numbers.

Rate of reaction: speed, frequency, level of energy, colliding particles.

Activation energy: Minimum amount of energy, collision.

Factors affecting rate of reaction: Surface area, stirring, concentration, temperature, catalyst, rate of removal.

Surface area: Smaller reactants = more surface area = greater reaction rate.

Stirring: Increase chance of collision.

Concentration of reactants: More reactant particles, higher chance collision, greater rate.

Temperature: Increase of temp = heat energy = kinetic energy = moving faster = increase rate of collision = increase rate of reaction.

Catalyst: Substance that increase rate of reaction without permanent chemical change.

Rate of removal of products: Not removed, reactants cannot collide to form products.