Notes, summaries, assignments, exams, and exercises for Chemistry for Secondary education

Understanding Chemical Oxides

Binary combinations between oxygen and all other chemical elements except the noble gases and fluorine.

Formulating Oxides

Oxides have the following general formula: X₂O_n, where:

• X is the symbol of the other element.
• 2 corresponds to the valence of oxygen.
• O is the symbol for oxygen.
• n is the valence of the other element (metal or nonmetal).

Naming Oxides: Three Classifications

Oxides are named using three classifications: Traditional, Systematic, and Stock.

Traditional Nomenclature for Oxides

Basic Oxides: These result from the combination of oxygen and a metal.

• If the metal has a single valence, the oxide is named "Oxide" followed by the name of the metal.

Examples:

• CaO: Calcium Oxide
• Na₂O: Sodium Oxide

• If the metal has two

IONIC: thet are solids at room temperatures and have medium to high meltin and boiling points. Ionic bond is strong because it is electrostatic. They are very hard. It is not eassy to scratch an ionic compound. They are fragile. Hitting them forces ions with the same signs together, and they repel and break the crystal. Most disolve well in water, water molecules may surround the ions,weakening their bonds and separating them from the crystal lattice. This is called solvation. They do not conduct electricity well in solid state but hey do in solution or liquid state. SODIUM CHLORIDE

Common Valences of Chemical Elements

This section details the typical valences (or oxidation states) for various chemical elements, grouped by their respective families in the periodic table.

Alkali Metals (Group 1)

• Li Lithium: Valence 1
• Na Sodium: Valence 1
• K Potassium: Valence 1
• Rb Rubidium: Valence 1
• Cs Cesium: Valence 1
• Fr Francium: Valence 1

Alkaline Earth Metals (Group 2)

• Be Beryllium: Valence 2
• Mg Magnesium: Valence 2
• Ca Calcium: Valence 2
• Sr Strontium: Valence 2
• Ba Barium: Valence 2
• Ra Radium: Valence 2

Transition Metals & Inner Transition Metals

Transition metals often exhibit multiple valences.

• Ti Titanium: Valences 3, 4
• Cr Chromium: Valences 2, 3, 6
• Mn Manganese: Valences 2, 3, 4, 6, 7
• Fe Iron: Valences 2, 3
• Co Cobalt: Valences 2, 3
• Ni Nickel: Valences

An ion is an atom which has more or less electrons than protons

Structure of the Atom

Protons, Electrons, and Neutrons

Protons: Equal to the atomic number

Electrons: Equal to the atomic number

Neutrons: Equal to the atomic mass minus the atomic number

Bohr-Rutherford Diagram

Electron shells: 2, 8, 8, 18, 18, 32

Counting Atoms

Example 1: Na₂CO₃

• Sodium (Na): 2
• Carbon (C): 1
• Oxygen (O): 3

Example 2: 4Al₂(CO₃)₃

• Aluminum (Al): 4 x 2 = 8
• Carbon (C): 3 x 4 = 12
• Oxygen (O): 9 x 4 = 36
• Total: 56

Ions and Ionic Compounds

Ions are atoms that have either lost or gained electrons. While atoms are neutral, ions are charged particles.

Ionic Compounds are a combination of a cation (positive ion) and an anion (negative ion), typically formed between a metal and a nonmetal.

Example: Calcium Chloride (CaCl₂)

Calcium (Ca⁺²) has a charge of +2,...

Ductility: Able to undergo change of form without breaking

·Malleability: capable of being shaped, as by Hammering or pressing:

·Density (give an Example): a measurement of how Tightly matter is crammed together. Example: Oil floats on vinegar because Its density is less.

• Chemical properties of matter (give an Example): Are any of the properties Of matter that may only be observed and measured by performing a chemical change or chemical Reaction. Example: oxidation states

·What is a physical Change (give an example): A usually reversible change in the physical 

properties of a substance,as size or shape. Example: When melting an ice cube.

·Difference between Chemical properties and physical properties (give an example)

Enthalpy, Rate Equations, and Halogens

Enthalpy Change of Solution

The enthalpy change that accompanies the dissolving of 1 mole of gaseous ions in H₂O to form 1 mol of aqueous ions is -1008/2 = -504 kJ mol^-1. F^- has a more exothermic hydration enthalpy as it has a smaller ionic radius, leading to a stronger attraction to H₂O molecules. The bond enthalpy for F-F is +158 kJ mol^-1.

Rate Equations and Reaction Mechanisms

For the reaction: Fe³⁺ + 2I^- --> FeI₂⁺, the rate equation is: rate = k[Fe³⁺][I^-]², where k = 22.5 dm⁶mol^-2s^-1. The mechanism for this reaction is a two-step process:

1. Fe³⁺ + 2I^- --> FeI₂⁺
2. Fe³⁺ + FeI₂⁺ --> 2Fe²⁺ + I₂

Halogens

Halogens have more electrons, leading to stronger London forces between molecules. This means more heat...

ACID OR BASES: Substances that react with each other according to the following reaction

Nucleus: The Center of an Atom

The nucleus is located at the center of an atom. It is very small and has a positive electrical charge due to the protons. The nucleus contains particles called protons and neutrons, which make up nearly all of the atom's mass.

Electron Cloud: The External Area of an Atom

The electron cloud surrounds the nucleus and is longer than the nucleus. It has an equal but negative electrical charge compared to the protons. The electron cloud contains particles called electrons, and their mass is negligible compared to the protons and neutrons.

Historical Development of Atomic Structure

In the 5th century, ancient Greeks proposed the concept of the atom. In 1808, Dalton discovered the existence of protons and electrons. In 1904,...

- Without H20 being polar, there would be no life on Earth, and Earth will be very dry. Humans and living organisims depend on H20 and it's polarity to sustain life on Earth because h20 wouldnt be able to form hydrogen bonds because it isnt polar. Animals who depend on ice such as polar bears and seals wold not be able to live due to ice not floating on the surface of water. When ice lacks crystal lattice structure, it starts to drown, and this happens due to the lack of hydrogen bonding. Therefore, h20 is very important for life to exist on earth.

- h-h: nonpolar covalent bond

- p-cl: covalent

- na-br: ionic

Electronegativity: 0->0.4 = covalent, 0.5->1.7=polar covalent, more than 1.7= ionic bonds, minus the EN

- Ion-induced dipole force: