Chem - Basics Flashcards
Matter
Both has mass and takes up space (volume)
Mass
How much matter
Weight
How much force
Substance
Matter of uniform and defined composition, made up of only 1 kind of matter
Element
A substance that cannot be broken down into simpler substances, simplest type of substance with unique properties
Law of definite proportions
A compound contains the same elements in the same proportions regardless of sample size and source
Empirical Formula
Lowest whole number of moles, gives relative number of atoms of each element in a compound
Molecular formula
Actual number of atoms of each element in a compound
Structural formula
Shows placement and connections of atoms in a molecule
Physical properties
Properties shown by the substance itself, without interactions with another substance
Chemical properties
Properties shown by a substance when it interacts with or transforms into other substances
Law of conservation of mass
Matter can neither be created nor destroyed
Solution
A homogeneous mixture of multiple substances
Miscible
A substance that is infinitely soluble in another substance
Dalton’s Atomic Theory
All matter is composed of atoms; atoms of one element are identical to each other and different than atoms of another element; atoms can only change when combined with other elements
Atomic number (Z)
Characteristic number of protons in the nucleus of atoms of a particular element, identifies element
N number (N)
Number of neutrons in the nucleus of an atom, identifies isotopes
Mass number (A)
Number of protons and neutrons in the nucleus of an atom, identifies mass
Isotope
An atom of an element with the same number protons but a different number of neutrons
Atomic Mass Unit (AMU)
A unit of mass equal to 1/12 the mass of a carbon-12 atom
Ion
An atom or group of atoms that has a positive or negative charge
Molarity (M)
Concentration of solute in a solution, M = n/L (molarity = moles solute/litres of solution)
Valence Electrons
Electrons involved in bond formation, typically held in the outermoat shell
Alkali metals
Basic in water, group 1 or IA
Alkaline Earth Metals
Group 2 or IIA
Transition Metals
Groups 3-12 or B groups
Halogens
Salt makers, group 17 or VIIA
Noble/Inert Gases
Full valence shell, stable, group 18 or VIIIA
Metals
Left of staircase; high heat and conductivity, malleable, ductile, lustrous, mostly solids
Nonmetals
Right of staircase; poor conductors, mostly gases
Metalloids
Border staircase; intermediate properties
Periodic Law
When elements are arranged by increasing atomic number properties will repeat and form patterns
Atomic size trend (periodic table)
Decreases across a period due to added protons having a stronger pull on the valence shell; increases down a group as additional shells are formed
Electron shielding
Core electrons block the nuclear charge over outer electrons
Electron shielding trend (periodic table)
Stays constant across a period due to containing the same number of core electrons; increases down a group as more core shells are added
Ionization energy (IE)
The amount of energy required for the complete removal of an electron from an atom or ion
Ionization energy trend (periodic table)
Increases across a period due to the stronger pull of protons on electrons; decreases down a group due to electrons being further from the nucleus and therefore shielded from proton attraction
Successive Ionization Energy
Energy required to remove successive electrons; increases with each electron due to increased positive charge, massive increase when full outer shell is removed and the new outer shell is complete
Cation
Loss of electron; positive charge, smaller atomic size
Anion
Addition of electron; negative charge, larger atomic size due to dilution of positive charge
Electronegativity
Ability of an atom in a covalent bond to attract the shared electron pair
Polar covalent bond
A bond in which the electron pair is not shared equally due to differences in electronegativity, causes the molecule to have partially charged regions
Electronegativity trend (periodic table)
Increases across period due to stronger positive force of protons on electrons; decreases down a group due to weaker positive force of protons on electrons
