S1.1 Introduction to the particulate nature of matter Flashcards
Element
An element is a substance that consists of only one type of atom and cannot be broken down into simpler substances by chemical means.
Compound
A compound is a pure substance composed of two or more different elements chemically combined in fixed ratios.
How does a mixture differ from a compound?
Mixtures which, unlike elements and
compounds, are not classified as pure substances.
Homogeneous
A type of mixture that a uniform composition and no visible phases or boundaries.
Heterogeneous
A type of mixture with a non-uniform composition with visible phases or boundaries.
What is meant by a “diatomic element” and provide three examples.
Diatomic elements are molecules composed of two atoms of the same element bonded together. Examples include hydrogen (H2), oxygen (O2), and nitrogen (N2).
Describe the difference between homogeneous and heterogeneous mixtures with examples.
Homogeneous mixtures have a uniform composition throughout, like salt water, while heterogeneous mixtures have visibly different phases or parts, like a mixture of oil and water.
What is filtration used for?
Filtration is used to separate an insoluble solid from a liquid or solution, such as separating sand from water.
Evaporation
A change of state from solid to gas; also a separation technique used to separate a homogeneous mixture.
Solvation
The interaction of a solvent with molecules or ions of a solute.
Distillation
A separation technique used to separate a mixture of two liquids with different boiling points of volatilities.
What principle does paper chromatography rely on for separation?
Paper chromatography separates solute mixtures by dissolving them in a solvent (mobile phase) and applying them to chromatography paper (stationary phase). Components move at varying rates due to solvation differences; those favoring the mobile phase travel further than those preferring the stationary phase.
Explain recrystallization as a separation technique.
It is a technique to purify solids by exploiting differences in solubility at various temperatures. Initially, the impure solid is dissolved in minimal hot solvent, allowing for the removal of insoluble impurities. Upon cooling, the solubility decreases, causing the desired solid to crystallize while leaving soluble impurities in solution. The crystals are then filtered to obtain the purified product.
What are the properties of solids
Solids are incompressible due to closely packed particles with minimal space between them, bound by strong forces of attraction. This results in solids having a fixed shape and volume, and they cannot flow.
How do liquids differ from solids in terms of particle arrangement?
Liquids can flow and take the shape of their container due to more spaced-out particles than in solids, though they still have a fixed volume.
Describe the properties of gases.
Gases do not have a fixed shape or volume, spreading out to fill the container, with particles far apart and weakly attracted to each other.
What is sublimation in the context of states of matter?
Sublimation is the process where a substance changes directly from a solid to a gas without passing through the liquid state.
What is the Kelvin scale?
The Kelvin scale is an absolute temperature scale where 0 K (absolute zero) represents a state where particles have zero kinetic energy.
How is Kelvin scale related to kinetic energy?
Temperature in Kelvin is directly proportional to the average kinetic energy of particles.
How to convert Celsius to Kelvin?
To convert Celsius to Kelvin, add 273. For example, 25 °C is equal to 298 K.
What happens to the kinetic energy of particles as temperature increases?
As temperature increases, the average kinetic energy of particles also increases, leading to changes in the state of matter.
Describe a heating curve and its significance.
A heating curve illustrates how the state of matter changes as heat is added, showing temperature plateaus during phase changes where heat is used to overcome intermolecular forces rather than increasing temperature.
Which phase changes involve absorption of heat?
Melting, evaporation (or boiling), and sublimation are phase changes that involve the absorption of heat.
