Separation Techniques and Measurements

Separation Techniques

• Filtration: Separates solid and liquid mixtures using a filter medium. The filter traps the solid while the liquid passes through.

• Chromatography: A lab technique used to separate components of a mixture based on their differing affinities for the stationary and mobile phases.

• Centrifugation: Separates components of a mixture based on their different densities using centrifugal force.

• Decantation: Separates a liquid from a solid by carefully pouring off the liquid, leaving the solid behind.

• Evaporation: Separates a solution by heating it until the solvent turns to vapor, leaving the dissolved solid behind.

• Magnetic Separation: Separates magnetic materials from non-magnetic materials by using a magnetic field to attract and separate the magnetic material.

Measurements

• Accuracy: How closely a measured value agrees with the correct value.
• Precision: How closely individual measurements agree with one another.

Atoms, Molecules, and Ions

• Atom: The smallest unit of matter.
• Molecule: A combination of two or more of the same atoms.
• Compound: A combination of two or more different atoms.
• Democritus proposed the concept of "atomos" (indivisible particles)

Atomic Structure

• Atomic Number (Z): The number of protons in an atom's nucleus.
• Mass Number: The sum of the number of protons and neutrons in an atom's nucleus.
• Proton: Positively charged particle in the atom's nucleus.
• Neutron: A neutral particle in the atom's nucleus.
• Electron: Negatively charged particle found outside the nucleus in electron shells.
• Ion: A charged atom or molecule.
• Isotopes: Atoms of the same element with different numbers of neutrons.

Chemical Bonds

• Ionic Bond: Forms between metal and nonmetal atoms as one atom transfers electrons to another.
• Covalent Bond: Forms when atoms share electrons. Usually between nonmetal atoms.

Representing Compounds

• Chemical Formula: Represents the elements present and their relative numbers in a compound.
• Molecular Formula: Shows the actual number of atoms of each element.
• Empirical Formula: The simplest whole-number ratio of atoms in a compound.
• Structural Formula: Shows the actual number of atoms and bonds between them.
• Molecular Models: 3D representations of molecules where atoms are represented by balls and bonds by sticks.

Atomic Theories

• Dalton's Atomic Theory: Introduced the concept of atoms as fundamental building blocks of chemical structures.
• Thomson's Plum Pudding Model: Proposed that atoms contain negatively charged electrons within a positively charged sphere.
• Rutherford's Nuclear Model: Suggested the existence of a dense, positively charged nucleus containing most of the atom's mass.
• Bohr's Planetary Model: Described electrons as orbiting the nucleus in specific energy levels or shells.
• Schrodinger's Quantum Model (Modern Model): Describes electrons as existing in orbitals/electron clouds.