Atoms- aqa

Keywords:

  • Atom: The basic unit of a chemical element, consisting of protons, neutrons, and electrons.

  • Element: A pure chemical substance consisting of one type of atom, distinguished by its atomic number.

  • Compound: A substance formed when two or more different elements chemically bond together.

  • Molecule: A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.

Notes: Aqa specification

  • All substances are made of atoms. An atom is the smallest part of an element that can exist.

  • Atoms of each element are represented by a chemical symbol, eg O represents an atom of oxygen, Na represents an atom of sodium.

  • There are about 100 different elements. Elements are shown in the periodic table.

  • Compounds are formed from elements by chemical reactions. Chemical reactions always involve the formation of one or more new substances, and often involve a detectable energy change. Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed. Compounds can only be separated into elements by chemical reactions.

  • Chemical reactions can be represented by word equations or equations using symbols and formulae.

  • Students will be supplied with a periodic table for the exam and should be able to:

    • use the names and symbols of the first 20 elements in the periodic table, the elements in Groups 1 and 7, and other elements in this specification

    • name compounds of these elements from given formulae or symbol equations

    • write word equations for the reactions in this specification

    • write formulae and balanced chemical equations for the reactions in this specification.

  • (HT only) write balanced half equations and ionic equations where appropriate.

At a glance:

1. Names and Symbols of Elements

- List the first 20 elements with their names and symbols (e.g., Hydrogen (H), Helium (He), etc.).

- Include elements in Group 1 (alkali metals) like Sodium (Na) and Potassium (K).

- Add elements in Group 7 (halogens) like Chlorine (Cl) and Fluorine (F).

2. Naming Compounds from Formulae

- Write examples of chemical formulas and their compound names, e.g.:

- H₂O = Water

- NaCl = Sodium Chloride

- CO₂ = Carbon Dioxide.

- Practice naming compounds formed by elements in Groups 1 and 7.

3. Writing Word Equations

- Write reactions using words, e.g.:

- Magnesium + Oxygen → Magnesium Oxide.

- Include examples of reactions from your course specification.

4. Balanced Chemical Equations

- Write formulas for reactions, e.g.:

- Mg + O₂ → MgO.

- Balance equations so the number of atoms is equal on both sides, e.g.:

- 2Mg + O₂ → 2MgO.

- Include examples from your specification.

5. Half Equations and Ionic Equations (HT)

- Half equations: Write electron transfer, e.g.:

- Cl₂ + 2e⁻ → 2Cl⁻.

- Ionic equations: Focus on ions involved, excluding spectator ions, e.g.:

- H⁺ + OH⁻ → H₂O.

- Add examples from your course.

1. Names and symbols of elements:

  • First 20 elements:

    1. Hydrogen (H)

    2. Helium (He)

    3. Lithium (Li)

    4. Beryllium (Be)

    5. Boron (B)

    6. Carbon (C)

    7. Nitrogen (N)

    8. Oxygen (O)

    9. Fluorine (F)

    10. Neon (Ne)

    11. Sodium (Na)

    12. Magnesium (Mg)

    13. Aluminium (Al)

    14. Silicon (Si)

    15. Phosphorus (P)

    16. Sulfur (S)

    17. Chlorine (Cl)

    18. Argon (Ar)

    19. Potassium (K)

    20. Calcium (Ca)

    Group 1 Elements (Alkali Metals):

    1. Lithium (Li)

    2. Sodium (Na)

    3. Potassium (K)

    4. Rubidium (Rb)

    5. Caesium (Cs)

    6. Francium (Fr)

    Group 7 Elements (Halogens):

    1. Fluorine (F)

    2. Chlorine (Cl)

    3. Bromine (Br)

    4. Iodine (I)

    5. Astatine (At)

    2. Naming Compounds from Formulae

    - Compounds are made by combining two or more elements.

    - To name a compound:

    - The first part of the name comes from the first element.

    - The second part of the name comes from the second element, ending in "-ide" (if only two elements) or "-ate" (if oxygen is included).

    Examples:

    1. H₂O = Water

    2. NaCl = Sodium Chloride

    3. CO₂ = Carbon Dioxide

    4. MgO = Magnesium Oxide

    5. CaCO₃ = Calcium Carbonate (ends with "-ate" because it contains oxygen).

    Group 1 and Group 7 Compound Examples:

    1. LiF = Lithium Fluoride

    2. KCl = Potassium Chloride

    3. Writing Word Equations

    - Word equations describe chemical reactions in words.

    - The format is: Reactants → Products.

    - Example 1: Magnesium + Oxygen → Magnesium Oxide.

    - Example 2: Sodium + Chlorine → Sodium Chloride.

    - Example 3: Hydrochloric Acid + Sodium Hydroxide → Sodium Chloride + Water.

    - Practice writing word equations for reactions from the specification.

    4. Balanced Chemical Equations

    - Chemical equations use symbols and formulas to represent reactions.

    - Ensure the number of atoms on both sides of the equation is equal (balanced).

    - Example 1 (unbalanced): H₂ + O₂ → H₂O.

    - Example 1 (balanced): 2H₂ + O₂ → 2H₂O.

    - Example 2 (balanced): Na + Cl₂ → 2NaCl.

    - Example 3 (balanced): Mg + O₂ → 2MgO.

    - Write and practice balancing equations from the course.

    5. Half Equations and Ionic Equations (HT)

    - Half equations show how electrons are transferred during reactions.

    - Example: Cl₂ + 2e⁻ → 2Cl⁻ (reduction: gain of electrons).

    - Ionic equations focus on the ions involved in the reaction, excluding spectator ions.

    - Example: H⁺ + OH⁻ → H₂O (formation of water).

    - Practice writing half and ionic equations for reactions in the specification.