1.1.1 Elements, Compounds & Mixtures Flashcards
Elements
Pure substances that cannot be broken down any further into simpler substances.
- E.g. hydrogen
What are the forms of elements? (5)
- Individual Atoms: single, unbonded atoms.
- E.g. Helium (He) - Molecules: atoms covalently bonded - the sharing of electron pairs bonds atoms.
- E.g. Oxygen (O2) - Giant Structures: atoms bonded in extended networks.
- E.g. Gold (Au), Carbon (C) - Diatomic Molecules: molecules found in nature as bonded pairs
- BrINCIHOF: Bromine (Br), Iodine (I), Nitrogen (N), Chlorine (Cl), Hydrogen (H), Oxygen (O), Fluorine (F). - Polyatomic Elements: 2 or more atoms in their natural forms.
- E.g. Phosphorus (P4), Sulfur (S4)
Compounds
Pure substances of (2 or more) different elements chemically bonded in fixed ratios.
- E.g. NaCl, H₂O
Mixtures
A combination of two or more pure substances where the components are in no fixed ratio, not chemically bonded, and retain their individual properties.
- Components do not need to be in the same state.
Homogenous Mixture
Mixtures with uniform composition throughout - 1 phase
- E.g. Saltwater
Heterogenous Mixture
Mixtures with ununiform composition - 2 separate phases
- E.g. sand + water, oil + water
Atom
The smallest particle of an element that retains the chemical properties of that element.
- E.g. Helium atom
Molecule
A group of two or more atoms, covalently bonded together, that behaves as a single unit.
- E.g., H₂O, CO₂, H₂
- can be same or different elements
Physical properties
Physical properties are characteristics of a substance that can be observed or measured without changing the substance’s chemical identity.
- E.g. Colour, odour, melting point, boiling point, density, mass, state, solubility
Acid
A substance that releases hydrogen ions (H⁺) when dissolved in water.
pH < 7
Base
A substance that releases hydroxide ions (OH⁻) in solution or accepts H⁺ ions.
pH > 7
Neutral
A substance with no overall charge (equal number of protons and electrons), or a solution with a pH of 7
Cation
A positively charged ion (formed when an atom loses electrons).
- E.g. Na⁺
Anion
A negatively charged ion (formed when an atom gains electrons).
- E.g. Cl⁻
Monotonic Ion
An ion made up of only one atom with a charge.
- E.g. Mg²⁺, O²⁻.
Polyatomic Ion
An ion made up of two or more atoms bonded together that carry a charge.
- E.g. SO₄²⁻ (sulfate)
Binary Acid
Acid with hydrogen and one other element.
- produce halogen ions in solutions
- name based on monotonic ion produced
Oxyacid
An acid containing hydrogen, oxygen, and a third element (usually a non-metal)
- produce polyatomic anions in solution
- name based on polyatomic anion produce
Acid-Base Reactions
Produce salt + water
- W.g. HCl (aq) + NaOH (aq) –> NaCl + H2O
