13-14 Flashcards
Define metals
Most are silver or grey in colour and shiny. Good conductors of electricity and heat. They are also malleable and ductile.
Define non metals
Most are gases. Highly reactive. An element that lacks the characteristics of a metal and is able to form anions, acidic oxides, acids, and stable compounds with hydrogen
Define metalloids
An element whose properties are intermediate between those of metals and solid non metals. They are electrical semiconductors
Define malleable
Able to be hammer or pressed permanently out of shape without breaking or cracking
Define ductile
Can be stretched and demeaned without losing toughness; pliable, not brittle
Define inert
Stable and unreactive under specified conditions
Define molecules
A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction
Define period
A set of elements occupying an entire horizontal row in the periodic table
Define group/family
A set of elements occupying a column in the periodic table and having broadly similar properties arising from their similar electronic structure
Define alkali metals
Any of the elements lithium, sodium, potassium, rubidium, cesium, and francium, occupying Group 1 of the periodic table, they are very reactive
Define alkaline earth metals
Any of the elements beryllium, magnesium, calcium, strontium, barium, and radium, occupying group 2 of the periodic table. They are reactive, electropositive, divalent metals, and form basic oxides that react with water to form comparatively insoluble hydroxides
Define noble gases
Any of the gaseous elements helium, neon, Aragon, krypton, xenon, and radon, occupying group 0 (18) of the periodic table. Mostly unreactive.
Define halogens
Any of the elements fluorine, chlorine, bromine, iodine, and astatine, occupying group 17 of the periodic table. They are reactive nonmetallic elements that form strongly acidic compounds with hydrogen, from which simple salts can be made.
Define salts
Any chemical compound formed from the reaction of an acid with a base
Define atom
The smallest part of an element that still has the properties of the element
Define energy level
The fixed amount of energy that a system described by quantum mechanics, such as a molecule, atom, electron, or nucleus can have
Define atomic number
The number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table
Define mass number
The total number of proteins and neutrons in a nucleus
Define atomic molar mass
Tells you the number of grams per mole of a compound
Define ionization
The process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons
Define ion
An atom or molecule with a net electric charge due to the loss or gain of one or more electrons
Define cation
A positive charged ion
Define anion
A negatively charged ion
Define valence electron
An outer shell electron that is associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed
Define octect rule
A chemical rule of thumb that reflects observation that atoms of main group elements ten to combine in such a way that each atom has eight electrons in its valence shell
The number of protons equals the?
Atomic number
The number of electrons equals the?
Atomic number minus the charge
The number of neutrons equals the?
Mass number minus the atomic number
Define crystal lattice
The symmetrical three dime is arrangement of atoms inside a crystal
Define formula unit
The empirical formula of any ionic or covalent network souls compound used as an independent entity for stoichiometric calculations
Define ionic bonding
A chemical bond formed between two ions with opposite charges
Define polyatomic ions
Also known as a molecular ion, is a charged chemical species composed of two or more atoms covalently bonded or of a metal complex that can be considered to be acting a a single unit
Define multivalent
Another term for polyvalent, having a valence of three or more
Define covalent bonds
A chemical bond that involves the sharing of electrons pairs between atoms
Define molecular element
Mostly diatomic non metals which exists as a molecule, that is, two or more atoms are bound and can exist independently and still retain the properties of that substance
Define diatomic
To consist of two atoms
Explain how to recognize an ionic compound from its chemical formula
Ionic compounds always contain positive and negative ions, you can recognize an ionic compound by noting the presence of a cation
List four properties of an ionic compound
1- high melting point
2- retention of crystal shape
3- solubility in water
4- conductivity in solution
Explain how to recognize a molecular compound by it’s chemical formula
Molecular compounds will only contain non metals. If the prefixes di-, tri-, etc, are used, the compound is molecular
List four properties of molecular compounds
1- low melting point
2-crystals do not hold their shape and crumble easily
3- poor conductors as solids and in a solution
4- attraction between neighbouring molecules is very weak.
Define polar molecule
An asymmetrical molecule with non uniform positive and negative charges. Has a partial positive charge in one part of the molecule and a negative charge in another part.
Define acid
A compound that dissolves in water to form a solution with a pH lower than 7
Define base
A compound that dissolved in water to form a solution with a pH greater than 7
Define pH
Indicates how acidic or basic a substance is
Define buffer
A substance that can keep the pH of a solution nearly constant despite the addition of a small amount of acid or base
Define neutral
A substance with a pH of 7, neither acidic or basic
Define neutralization
When acids and bases react together and both basic and acidic properties disappear
Formula for water
H2O
Formula for hydrogen peroxide
H2O2
Formula for ammonia
NH3
Formula for sucrose
C12H22O11
Formula for methane
CH4
Formula for propane
C3H8
Formula for methanol
CH3OH
Formula for ethanol
C2H5OH
Formula for hydrogensulphide
H2S
Define electrolyte
A liquid or gel that contains ions and can be decomposed by electrolysis
