Ions, Anions, and Cations

Terminology

• An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a charged species
• A cation is a positively charged ion, formed when an atom loses electrons
• An anion is a negatively charged ion, formed when an atom gains electrons
• Ionic charge is the charge on an ion, it can be positive (cation) or negative (anion) and is determined by the loss or gain of electrons
• Combining capacity is an element's ability to combine with other elements to form compounds, often represented by valency or the number of bonds an element can form
• A valence electron is found in the outermost shell of an atom and is responsible for forming bonds
• A stable octet refers to the concept that atoms tend to gain, lose, or share electrons to have eight electrons in their outer shell, mimicking the electron configuration of noble gases
• A polyatomic ion is composed of two or more atoms, usually held together by covalent bonds, and carries an overall charge
• A binary compound is a chemical compound that contains exactly two different elements, usually one metal and one non-metal
• A ternary compound is a chemical compound composed of three different elements, often involving a metal and two non-metals
• An ionic bond is a chemical bond formed through the electrostatic attraction between positively and negatively charged ions, typically between metals and nonmetals
• A covalent bond happens when two atoms share one or more pairs of electrons, typically between two nonmetals
• A molecule is a neutral group of two or more atoms held together by covalent bonds
• A binary covalent compound is formed by two nonmetals held together by covalent bonds, and is often a molecule like CO2 (carbon dioxide)
• A reactant is a substance that undergoes a chemical change during a reaction and is found on the left side of a chemical equation
• A product is a substance produced in a chemical reaction and is found on the right side of a chemical equation
• A chemical reaction is a process in which one or more substances (reactants) are converted into different substances (products)
• A chemical equation is a symbolic representation of a chemical reaction, showing the reactants and products, their physical states, and coefficients to balance the equation
• A coefficient is the number placed in front of a chemical formula in a chemical equation to balance the equation and represent the relative amounts of reactants and products
• An acid is a substance that donates protons (H+) in a solution and typically has a pH less than 7
• A base is a substance that accepts protons (H+) or donates hydroxide ions (OH-) in a solution, typically having a pH greater than 7
• Ionization refers to the process by which an atom or molecule gains or loses electrons, forming ions; with acids and bases, it's the dissociation into ions
• Dissociation is the process by which an ionic compound breaks into its constituent ions in a solution
• The pH scale measures the acidity or basicity of a solution, ranges from 0 (strongly acidic) to 14 (strongly basic), with 7 being neutral
• Neutralization is a chemical reaction between an acid and a base, resulting in the formation of water and a salt, typically reducing the acidity or basicity of the solution

Matter

• Matter is anything that has mass and takes up space
• Matter does not come in the form of energy such as sound, light, or heat
• Matter is classified by chemical and physical properties

Properties and Changes

• Physical properties are those that can be physically seen, such as colour, smell, and taste
• Chemical properties refer to properties that involve a chemical reaction, such as fire, pH, reactions with acid, and solubility
• Physical changes alter the appearance or state of matter without altering its chemical composition, such as water freezing or crushing a can
• Chemical changes involve a reaction/change that makes a new substance with different chemical properties and is irreversible, such as baking a cake

Pure Substances vs Mixtures

• Pure substances are elements and compounds
• Mixtures can be classified as homogeneous or heterogeneous
• Homogeneous mixtures have ingredients that can not be seen and are a solution like orange juice, water, or pop
• Heterogeneous mixtures have ingredients that can be seen, like a mechanical mixture such as pizza or a chocolate chip cookie

The Periodic Table

• Metals are on the left side, and non-metals are on the right side
• A period is a row
• The number of electron shells an atom has determines the period it belongs to
• A group is a vertical column
• The number of electrons in the outermost shell determines the group
• The atomic number is the little number on the top left
• It represents the number of electrons orbiting the nucleus
• Atomic mass is the total number of protons and neutrons in an atomic nucleus
• Valence electrons are electrons on the outermost shell of an atom

Families on the Periodic Table

• Alkali earth metals are in group 1a
• Alkaline earth metals are in group 2a
• Transition metals are in the middle group
• Halogens are in group 7a
• Noble gases are in group 8a
• Metalloids are on the staircase

Drawing Bohr-Rutherford Diagrams

• Draw the nucleus as a solid circle
• Put the number of protons (atomic number) in the nucleus with the number of neutrons
• To find the number of neutrons, subtract the atomic number by the atomic mass
• Place the number of electrons in orbits around the nucleus by drawing circles
• The 1st shell holds 2 electrons, the 2nd shell holds 8 electrons, and the 3rd shell holds 8 electrons

Atoms vs Ions

• Atoms are electrically neutral
• The number of protons equals the number of electrons
• Protons are positively charged particles found in the center of the atom, in the nucleus
• Electrons are negatively charged particles that orbit the nucleus
• Neutrons are electrically neutral particles located in the nucleus
• Protons equal the atomic number
• Electrons equal the atomic number
• Neutrons = mass number - atomic number
• Ions are atoms that have become charged by gaining or losing electrons
• Cations are ions with a positive charge and have lost electrons
• Anions are ions with a negative charge and have gained electrons

Types of Compounds

• Binary ionic compounds happen when a metal reacts with a nonmetal
• Roman numerals identify the charge of the transition metal when it mixes with a nonmetal, because it has more than one charge
• Roman numerals still follow the criss-cross rule

Examples of Ionic Compounds (Criss-Cross)

• KCI - Potassium chloride
• Li₂O- Lithium Oxide
• CaBr₂- Calcium Bromide
• Always add "ide"

Writing Ionic Formulas (Criss-cross)

• Silver oxide - Ag₂O
• Aluminum nitride - Al₃N₃
• Magnesium nitride - Mg₃N₂
• Calcium hydride- CaH₂

Binary Covalent Compounds (Molecular)

• These form when two nonmetals react with each other
• Covalent prefixes are added to the name of covalent compounds if there are charges in the formula

Covalent Prefixes

• 1 is Mono
• 2 is Di
• 3 is Tri
• 4 is Tetra
• 5 is Penta

Polyatomic Ions

• These are groups of two or more atoms that stick together, have an overall charge, and act like a single unit in chemical reactions
• Sulfate (SO₄²⁻) has one sulfur atom and four oxygen atoms, with a -2 charge.
• Ionic Compounds + Polyatomic ions - Only Criss-Cross the charge outside of the bracket

Example of Ionic Compounds + Polyatomic Ions

• Ba(NO₃)² = Ba₂NO₃

Word Equations + Skeleton Equations + Balancing Chemical Equations

• Word equations use the names of the substances involved in chemical reactions
• Reactant 1 + Reactant 2 yields Product 1 + Product 2
• Use roman numerals for transition metals without criss-crossing
• Skeleton equations use chemical formulas to represent chemical reactions
• Skeleton equations do not include coefficients to balance the reaction
• The criss-cross method must be applied
• Balancing chemical equations is the process of ensuring the number of atoms for each element is the same on both sides of a chemical reaction

Law of Conservation

• "Any given chemical reaction, the total mass of the reactants is always the SAME as the total mass of the products"

Example of Balancing Chemical Equations

• _Fe + _H₂SO₄ -> _Fe₂(SO₄)₃ + _H₂
• 2Fe + 3H₂SO₄ -> _Fe₂(SO₄)₃ + 3H₂

Diatomic Molecules

• These will automatically have a charge of 2 if seen by itself in an equation
• IHNFCLBRO (H₂, N₂, O₂, Cl₂, Br₂, I₂, and F₂)

Classifying Chemical Reactions

• Synthesis happens when two simple elements (reactants) combine to form one larger, more complex molecule (product)
• General Pattern: A + B yields AB
• Decomposition is the opposite of a synthesis reaction
• General Pattern: AB yields A + B
• Single displacement: one element displaces another element in a compound
• General pattern: A + BC yields AC + B
• Metals will replace metals, and non-metals will replace non-metals

Double Displacement

• This happens when two elements in different compounds trade places
• General Pattern: AB + CD yields AD + BC
• Metals each replace one another, and non-metals each replace one another

Combustion Reaction

• A fuel burns or reacts rapidly with oxygen
• Combustion reactions release energy in the form of heat and light

Acids and Bases

• Acids are aqueous solutions that conduct electricity, taste sour, turn blue litmus red, and neutralize bases
• Bases are aqueous solutions that feel slippery, taste bitter, conduct electricity, and turn red litmus blue

pH Scale

• The pH scale measures the power of hydrogen
• It is a measure of the concentration of hydrogen ions (H+) in a solution
• It goes up in increments of 10; a pH of 1 is 10x more acidic than a pH of 2
• Solutions with a high concentration of hydrogen ions are Acidic
• Solutions with a low concentration of hydrogen ions are Basic or Alkaline
• The scale ranges from 0 - 14
• pH 0 is most acidic, with a high concentration of H+
• pH 14 is most basic, with a low concentration of H+ and high concentration of OH-
• pH 7 is neutral, with equal concentrations of H+ and OH-

Naming Acids

• Binary acids are acids made of elements
• Oxyacids are acids made of polyatomics

Writing the Formulas of Acids

• Always add hydro to the beginning (H if it is a formula)
• Always use the criss-cross method with charges
• "Ite" becomes "ous"
• "Ate" becomes "ic"
• Still use the criss cross method if a roman numeral is next to a transition element

Rules for Oxyacids

• Drop the "Hydro" and keep the H in the formula
• Add Acid at the end of every Acid
• "Ite" becomes "ous"
• "Ate" becomes "ic"