IB Chem flashcards

Atom

Smallest part of an element.

Element

A substance that cannot be broken down by any chemical process into simpler substances.

Mole

The amount of substance that contains the same number of entities as there are atoms in exactly 12 grams of carbon-12.

Molar mass

The mass of one mole of a substance, expressed in grams per mole (g/mol).

Avogadro constant

6.022 x 10^23 mol^-1, the number of entities in one mole of a substance.

Composition of an atom

Consists of a nucleus with protons and neutrons, surrounded by electrons in orbitals.

Atom vs

Atom is neutral with protons = electrons; ion is charged with unequal protons and electrons.

Atomic radius trend

Decreases across a period, increases down a group.

Ionization energy

Energy to remove electrons; increases across a period, decreases down a group.

Formation of ionic bond

Transfer of electrons from metal to non-metal, forming positive and negative ions.

Electronegativity

Atom's ability to attract electrons; increases across a period, decreases down a group.

Enthalpy change

Heat energy in a reaction at constant pressure.

Hess's Law

Total enthalpy change is the same regardless of reaction steps.

Rate of reaction

Change in concentration per unit time.

Effect of temperature on rate

Increase in temperature leads to higher reaction rate.

Dynamic equilibrium

Rates of forward and reverse reactions are equal; concentrations remain constant.

Le Chatelier's Principle

System shifts equilibrium to counteract changes.

pH

Measure of hydrogen ion concentration; -log[H⁺].

Strong vs

Strong acid fully dissociates; weak acid partially dissociates.

Oxidation vs

Oxidation is electron loss; reduction is electron gain.

Oxidizing and reducing agents

Cause oxidation/reduction in other substances.

Homologous series

Organic compounds with the same functional group, differing by CH2.

Structural isomerism

Same formula, different atom arrangements.

Accuracy vs

Closeness to true value vs. closeness of measured values.

Random vs

Fluctuations vs. consistent errors.

Electronic configuration of Mg

1s² 2s² 2p⁶ 3s².

First ionization energy trend

Increases across period 3 (Na to Cl).

Atomic radius down a group

Increases due to added energy levels.

Covalent bond

Sharing electron pairs between atoms.

Bonding in methane (CH₄)

Four covalent bonds between carbon and hydrogen.

Standard enthalpy change

Enthalpy change under standard conditions.

Enthalpy change calculation

Energy absorbed = (4 × H–O) - [(2 × H–H) + (1 × O=O)].

Rate equation

Relationship between reaction rate and reactant concentrations.

Catalyst effect

Increases rate by providing lower activation energy pathway.

Dynamic equilibrium

Rates of forward and reverse reactions are equal; concentrations remain constant.

Pressure effect on equilibrium

Favors side with fewer gas moles.

Conjugate acid-base pair

Substances related by proton loss or gain.

pH calculation for HCl

pH = -log(0.10) = 1.0.

Balanced redox reaction

5Fe²⁺ + MnO₄⁻ + 8H⁺ → 5Fe³⁺ + Mn²⁺ + 4H₂O.

Oxidizing and reducing agents

Cl₂ is oxidizing agent; Fe is reducing agent.

Functional group

Group of atoms responsible for molecule's characteristic reactions.

Isomer of butane

Isobutane (2-methylpropane).

element

a substance that cannot be broken down into simpler substances.

atom

smallest part of an element.

compound

substance that contains more than one element.

empirical formula

this shows the simplest whole number ratio of atoms of each element in a particle of the substance.

molecular formula

shows the actual number of atoms of each element in a molecule of the substance.

structural formula

this shows the arrangement of atoms an dbonds within a molecule.

molar mass

the mass of one mole of any substance.

relative atomic mass

the weighted mean of all the naturally occurring isotopes of the elemtn relative to carbon-12

concentration

the amount of solute (dissolved substance) in a known volume of solution (solute plus solvent).

standard solution

a solution of known concentration.

ideal gas

a gas that obeys the gas laws

real gases

a gas that hase some attractive force between the particles and do occupy some space so they do not exactly obey the gas laws.

nucleons

all the collective protons and neutrons

mass number

equal to the number of protons and neutrons in the nucleus of an atom

atomic number

equal to the number of protons in the nucleus and to the number of electrons in the atom

isotope

atoms of the same element with the same number of protons but with different number of neutrons

mass spectrometer

vaporized sample is injected, ionized by being bombarded with a beam of electrons until one electron is shoved off, accelerated through parallel plates where the ion is under the influence of an electric field, deflected by a magnetic field depending on mass and charge, and detected.

radioisotopes

isotopes of elements whose nuclei break down spontaneously. they are used in nuclear power generation, the sterilization of surgical instruments, crime detection, finding cracks in metals, and food preservation.

line spectrum

each element has its own characteristic spectrum that is not continuous

first ionization energy

the energy required to remove one electron from an atom in its gaseous state

electronic configuration

the arrangement of electrons in an atom

valence electrons

the electrons in the highest energy level

group

vertical columns in the periodic table that holds elements with the same number of valence electrons

period

horizontal rows in the periodic table that holds elements with the same number of occupied energy shells

atomic radius

the distance from the nucleus to the outermost electron

cation

positive ion. contain fewer electrons than protons so the electrostatic attraction between the nucleus and the outermost electron is greater and ion is smaller than the parent atom.

anion

negative ion. contain more electrons than protons so it is larger than the parent atom.

periodicity

the repeating pattern of physical and chemical properties shown by the different periods.

monoatomic molecule

molecule with a single atom

electronegativity

a relative measure of the attraction an atom has for a shared pair of electrons when it is covalently bonded to another atom

metalloid

an element that possesses some of the properties of a metal and some of a non-metal

amphoteric

substance that can be either acidic of basic.

Ionic bond

when electrons are transferred from one atom to another to form ions with complete outer shells of elections.

Covalent bond

involves the sharing of one or more pairs of electrons so that each atom in the molecule achieves an inert gas configuration.

lewis dot structure

it is the electron dot structure in which all the valence electrons are shown

polar bond

when their is an unequal distribution of charge in a molecule

valence shell electron pair repulsion

this states that pairs of electrons arrange themselves around the central atom so that they are as far apart from eachother as possible

Van der waals

forces that are created when an instantaneous dipole induces another dipole in a neighboring particle resutling in a weak attraction between the two particles

metallic bond

the attraction that two neighboring positive ions have for the delocalized electrons between them

exothermic

when the heat is given out to the surroundings; the bonds in the products are stronger than the bonds in the reactants

endothermic

heat is absorbed; bonds in the reactants are stronger than the bonds in the products

heat

a measure of the total energy in a given amount of substance

temperature

a measure of the average kinetic energy of the substance

enthalpy

the internal energy stored in the reactants

average bond enthalpy

can only be measured if products and reactants are in a gaseous state.

Hess's law

enthalpy change for a reaction depends only on the difference between the enthalpy of the products and the enthalpy of the reactants.

rate of reaction

the increase or decrease in concentration of one of the products per unit time

collision theory

for a reaction to occur, the particles must collide, they must collide with the proper orientation, and they must collide with enough force to bring about the reaction.

activation energy

the minimum amount of energy required for a reaction to occur

equilibrium

when the rate of the forward reaction is equal to the rate of the reverse reaction, and both reactions continue to take place

closed system

a system in which neither matter nor energy can be lost or gained

le chatelier's principle

if a system at equilibrium is subjected to a small change the equilibrium tends to shift so as to minimize the effect of the change

acid

a substance which produces hydrogen ions

base

a substance than can neutralize an acid

Bronsted-Lowry Acid

substance that donates a proton

Bronsted-Lowry Base

susbtance that accepts a proton

Lewis Base

substance that donates a pair of electrons

Lewis Acid

substance that accepts a pair of electrons