Electron Configuration of Neutral Atoms and Ions

Electron Configuration of Neutral Atoms and Ions

• Electron configuration is a shorthand way to show the arrangement of electrons in an atom
• It is written in the order of increasing energy levels (1s, 2s, 2p, 3s, 3p, etc.)
• The number of electrons in each energy level is indicated by a superscript
• For neutral atoms, the number of electrons is equal to the atomic number
• For ions, the number of electrons is different from the atomic number due to gain or loss of electrons

Formation of Positive and Negative Ions

• Positive ions (cations) are formed when an atom loses one or more electrons
• Negative ions (anions) are formed when an atom gains one or more electrons
• The number of electrons lost or gained is indicated by the charge on the ion
• For example, Na (sodium) loses one electron to form Na+ (sodium ion), and Cl (chlorine) gains one electron to form Cl- (chloride ion)

Formation of Covalent and Ionic Bonds

• Covalent bonds are formed when two or more atoms share one or more pairs of electrons
• Ionic bonds are formed when one or more electrons are transferred from one atom to another
• Covalent bonds typically form between non-metal atoms, while ionic bonds typically form between metal and non-metal atoms

Properties of Metals

• Metals are typically shiny, malleable, and good conductors of electricity
• They tend to lose electrons to form positive ions
• Reactivity of metals increases as you move down a group in the periodic table

Writing Formulas using Data Booklet

• The formula of a compound is written using the symbols of the atoms involved and the ratio of atoms in the compound
• The data booklet provides the atomic numbers and symbols of elements
• For example, the formula for calcium carbonate is CaCO3, where Ca is calcium, C is carbon, and O is oxygen

Types of Chemical Reactions

• Chemical reactions involve the transformation of one or more substances into new substances
• Types of chemical reactions include:
  • Synthesis reaction: two or more substances combine to form a new substance
  • Decomposition reaction: a single substance breaks down into two or more substances
  • Replacement reaction: one substance replaces another substance in a compound
  • Combustion reaction: a substance reacts with oxygen to produce heat and light

Precipitation Reactions

• A precipitation reaction is a type of reaction where two solutions react to form an insoluble solid (precipitate)
• The precipitate can be identified by its colour, shape, and solubility
• For example, the reaction between silver nitrate and sodium chloride solutions produces a white precipitate of silver chloride

Balancing Equations

• A balanced equation is a chemical equation where the number of atoms of each element is equal on both the reactant and product sides
• The equation is balanced by adding coefficients (numbers) in front of the formulas of the reactants and products

Acids and Bases

• Acids are substances that donate H+ ions (hydrogen ions) in solution
• Bases are substances that accept H+ ions in solution
• The difference between acids and bases is the presence of H+ ions
• Neutralisation reaction: an acid reacts with a base to form a salt and water

Hydrocarbons

• Hydrocarbons are compounds that contain only hydrogen and carbon atoms
• They can be identified by their molecular formula and structural formula
• For example, methane (CH4) is a hydrocarbon with a molecular formula of CH4 and a structural formula of H-C-H-H-H
• Hydrocarbons can be drawn using dashes and wedges to represent the bonds between atoms

Electron Configuration

• Electron configuration is a shorthand way to show the arrangement of electrons in an atom, written in the order of increasing energy levels (1s, 2s, 2p, 3s, 3p, etc.)
• The number of electrons in each energy level is indicated by a superscript
• For neutral atoms, the number of electrons is equal to the atomic number
• For ions, the number of electrons is different from the atomic number due to gain or loss of electrons

Formation of Ions

• Positive ions (cations) are formed when an atom loses one or more electrons
• Negative ions (anions) are formed when an atom gains one or more electrons
• The number of electrons lost or gained is indicated by the charge on the ion

Formation of Bonds

• Covalent bonds are formed when two or more atoms share one or more pairs of electrons
• Ionic bonds are formed when one or more electrons are transferred from one atom to another
• Covalent bonds typically form between non-metal atoms, while ionic bonds typically form between metal and non-metal atoms

Metals

• Metals are typically shiny, malleable, and good conductors of electricity
• They tend to lose electrons to form positive ions
• Reactivity of metals increases as you move down a group in the periodic table

Writing Formulas

• The formula of a compound is written using the symbols of the atoms involved and the ratio of atoms in the compound
• The data booklet provides the atomic numbers and symbols of elements

Chemical Reactions

• Chemical reactions involve the transformation of one or more substances into new substances
• Types of chemical reactions include:
  • Synthesis reaction: two or more substances combine to form a new substance
  • Decomposition reaction: a single substance breaks down into two or more substances
  • Replacement reaction: one substance replaces another substance in a compound
  • Combustion reaction: a substance reacts with oxygen to produce heat and light

Precipitation Reactions

• A precipitation reaction is a type of reaction where two solutions react to form an insoluble solid (precipitate)
• The precipitate can be identified by its colour, shape, and solubility

Balancing Equations

• A balanced equation is a chemical equation where the number of atoms of each element is equal on both the reactant and product sides
• The equation is balanced by adding coefficients (numbers) in front of the formulas of the reactants and products

Acids and Bases

• Acids are substances that donate H+ ions (hydrogen ions) in solution
• Bases are substances that accept H+ ions in solution
• The difference between acids and bases is the presence of H+ ions
• Neutralisation reaction: an acid reacts with a base to form a salt and water

Hydrocarbons

• Hydrocarbons are compounds that contain only hydrogen and carbon atoms
• They can be identified by their molecular formula and structural formula
• Hydrocarbons can be drawn using dashes and wedges to represent the bonds between atoms