Science Notes 2025 Flashcards
(19 cards)
What are the two components of a word equation in chemical reactions?
Reactants (Initial Substances) and Products (Substances formed during a reaction)
Reactants always go on the left and products on the right.
What must be true for a balanced chemical equation?
The same number of each element on both sides of the equation
Atoms can’t be created or destroyed in a reaction.
What should never be changed to balance a chemical equation?
Subscripts
Only coefficients can be changed.
What is the crossover rule for writing ionic formulae?
Crossover the charges from top to bottom
Ensure to remove the + and - symbols.
What defines a synthesis reaction?
Combines all the reactants to form a product
Recognized by a product that contains all the reactant atoms.
What is ionic bonding?
Transfer of electrons from one element to another
Results in the formation of charged species or ions.
What are the properties of ionic substances?
- Solid crystals at room temperature
- Extremely high melting and boiling points
- Conduct electricity when in solution or melted
- Strong rigid lattice structure
- Hard and brittle
- Good insulators when solid
What affects the structure of an ionic compound?
The relative sizes of cations and anions
Ionic compounds include salts, oxides, hydroxides, and sulphides.
What is a decomposition reaction?
A compound breaks down into two or more substances
It is the opposite of a combination reaction.
What energy forms are generally required for decomposition reactions?
Heat, light, or electricity
Most decomposition reactions are endothermic.
What happens during a single displacement reaction?
One element is substituted for another element in a compound, generating a new element and a new compound
Requires a metal and an ionic compound.
What are the products of an acid and metal reaction?
Salt and Hydrogen
Example: Zinc metal reacts with Hydrochloric acid.
What are the products of an acid and metal carbonate reaction?
A salt, water, and carbon dioxide gas
Example: Magnesium Carbonate reacts with Hydrochloric acid.
What are the products of a neutralization reaction?
A salt and water
Example: Sodium Hydroxide reacts with Hydrochloric acid.
Fill in the blank: Atoms are most stable when they have a _______.
full outer shell of electrons
True or False: Ionic compounds conduct electricity in solid state.
False
They conduct electricity in molten state or when dissolved in solution.
What is the main characteristic of the physical properties of ionic compounds?
They are hard and brittle
Due to strong electrostatic forces of attraction between ions.
What type of reaction is characterized by the breaking of bonds between reactants and forming new bonds in products?
Chemical reactions
What must be done last when balancing chemical equations?
Balance the H and O elements
It is recommended to balance these elements last.
