Untitled Quiz

Learning Outcomes

• Three states of matter: solid, liquid, gas
• Changes of state: melting, freezing, vaporization, condensation, sublimation, deposition
• Atoms, molecules, and ions
• Separating and purifying substances
• Filtration, separating funnel, crystallization, distillation, paper chromatography
• Criteria of purity
• Elements and compounds
• Atomic theory
• Kinetic model and changes of state
• Diffusion
• Atomic structure and subatomic particles
• Proton number
• Nucleon number
• Isotopes
• Relative atomic mass
• Arrangement of electrons in atoms

States of Matter

• Matter is anything that has mass and takes up space
• Matter exists as a solid, liquid, gas, and plasma
• Solids have a definite shape and volume, high density, incompressible and low diffusivity
• Liquids have a defined volume but adapt to the shape of their container, high density, and incompressible
• Gases have no definite shape or volume but adapt to the shape and volume of their container, low density and compressible

States of Matter Properties

• Solid: fixed shape, fixed volume, high density, incompressible, low diffusivity

• Liquid: fixed volume, takes shape of container, high density, incompressible

• Gas: takes shape and volume of container, low density, compressible, widely spaced particles

• Plasma: fourth state of matter, electrically charged gas

Changes of State

• Melting point (m.p.): temperature at which a solid changes to a liquid
• Boiling point (b.p.): temperature at which a liquid changes to a gas
• Evaporation: change of liquid to gas at a temperature below the boiling point
• Sublimation: change of solid to gas without becoming a liquid
• Deposition: change of gas to solid without becoming a liquid
• Condensation: change of gas to liquid

Kinetic Model Theory

• All matter is made up of tiny particles
• All particles are in constant random motion
• The arrangement of particles is different for each state (solid, liquid, gas)
• The more often the particles collide with the walls of the container, the greater the pressure

Kinetic Model Theory (Continued)

• Particles in gases move very quickly and randomly
• Particles in liquids move more slowly than those in gases but faster than those in solids
• Particles in solids vibrate in fixed positions

Pure Substances vs. Mixtures

• Pure substance: single substance, invariant chemical composition, distinct properties

• Mixture: two or more pure substances, retain individual identities, separated by physical methods

• Homogeneous mixture: mixtures with uniform composition & properties throughout (solution)

• Heterogeneous mixtures: mixtures that are not uniform in their composition & properties

Separating Techniques

• Decantation: pouring off the liquid after a solid settles at the bottom
• Filtration: separates a solid from a liquid (insoluble)
• Centrifugation: isolates solid based on density difference
• Separating funnel: separates immiscible liquids based on density
• Evaporation: method to obtain a soluble solid from a solution by evaporating the liquid
• Crystallization: separates a soluble solid from a solution by cooling

Separating Techniques (Continued)

• Fractional distillation: separates miscible liquids based on differences in boiling points
• Chromatography: method of separating components of different solubility in a solvent
  • Different substances move across the chromatography paper at different speeds based on their interactions with the solvent
• Paper chromatography: separation of components of a mixture using paper and a solvent
• Rf value: ratio of how far a material travels on the paper to the solvent front

Diffusion

• spreading of particles from a region of higher concentration to a region of lower concentration

Impurities Effects on Melting & Boiling Points

• Impurities in a substance lower its melting point and raise its boiling point
• The changes in melting and boiling points may spread over a range of temperatures

Phase Change Diagrams & Heating/Cooling Curves

• Graphical representations of physical states of a substance under varying temperature and pressure conditions
• Heating curves for pure substances show a constant temperature during phase changes (melting, boiling)
• Heating curves for mixtures show a range of temperature during phase changes

Water & Ice

• Salt lowers the freezing point of ice, speeding up the melting of ice.

Definitions

• Volatility: tendency of a substance to evaporate at normal temperatures
• Solvent: substance capable of dissolving other substances (usually a liquid)
• Solute: substance dissolved by the solvent

Classification of Matter (Elements & Compounds)

• Element: pure substance composed of only one type of atom, cannot be broken down into simpler substances
• Compound: pure substance composed of two or more different types of elements chemically bonded in a fixed ratio

Atomic Theory Development

• Various scientists like Democritus, Dalton, Thomson, Rutherford, Bohr and Schrödinger contributed to understanding the atom

Element Identification

• Symbols: elements are represented with a unique symbol(one or two letters)

Chemical Language

• Dalton proposed elements should have unique symbols

More Definitions

• Atom: basic unit of matter
• Molecule: group of two or more atoms joined together by chemical bonds
• Ion: atom or molecule with a net electric charge

Kinetic Model and Diffusion Properties

• Heavier particles move more slowly than lighter ones. Also bigger molecules diffuse slower than smaller ones
• Pressure of a gas is from collisions of particles with the container walls.
• Heat increases the average speed of particles