Q2: Gen Bio Flashcards
father of atomism, focused on the ultimate components of all substances.
Believed that Matter is ultimately composed of indivisible particles, with nothing between them but empty space.
DEMOCRITUS (c.460-370 BC)
atoms Greek atomos, “”
uncuttable
held that it was impossible for “nothing” to exist, and his influence suppressed the concept of atoms for 2000 years.
ARISTOTLE (384-322 BC)
Further studies in the 18TH CENTURY gave rise to ______
laws concerning the relative masses of substances that react with each other.
- 2 mass laws discovered (law of mass conservation, law of definite proportions)
At the beginning of the 19TH CENTURY,______________
John Dalton proposed an atomic model that explained these mass laws.
Early 20TH CENTURY gave rise to ________________
a picture of the atom with a complex internal structure, which led to our current model.
matter having an invariant chemical composition and distinct properties
PURE SUBSTANCE
fundamental substance, cannot be separated into simpler substances by chemical methods
- Simplest type of matter with unique physical and chemical properties
- Consist of only one kind of atom
- Substance, matter whose composition is fixed
Element
Why are each element unique?
because the properties of its atoms are unique
Most elements exist in nature as ____
population of atoms
an independent structure consisting of 2 or more atoms chemically bound together.
molecules
substance composed of 2 or more elements in Fixed proportion; can be separated into simpler substances and elements only by chemical methods
- type of matter composed of two or more different elements that are chemically bound together.
Compound
consists of fixed numbers of atoms of the component elements.
Compound
T or F. properties of compounds are different from those of its component elements
T
What process do compounds undergo during its breakdown
Chemical change/Chemical process
matter consisting of 2 or more pure substances that retain their individual identities and can be separated by physical methods since they are physically intermingled
MIXTURE
T or F. components of a mixture don’t vary in their parts by mass.
F - components of a mixture can vary in their parts by mass.
T or F. A mixture retains many of the properties of its components.
T
Unlike compounds, mixtures can be separated into their components by________
by physical changes;
mixture having a uniform composition and properties throughout
- also called??
Homogeneous ; Solution
no visible boundaries because the components are mixed as individual atoms, ions, and molecules.
Homogeneous Mixture
T or F. We have no way to tell visually whether an object is a substance (element or compound) or a homogeneous mixture.
T
T or F. Solutions can only exist in the liquid state
F - can exist in all 3 physical states
mixture not uniform in composition and properties throughout.
Heterogeneous
has one or more visible boundaries between the components
Heterogeneous mixture
most elements consist of a large collection of ___________ atoms
identical
Mixtures differ fundamentally from compounds in three ways:
- the proportions of the components can vary
- the individual properties of the components are observable;
- the components can be separated by physical means
Separation of mixture though hands
HANDPICKING
separates the grains from the stems or stalks. this is beating wheat or paddy stems to separate grains from the stems and the chaff that covers the grains
THRESHING
process of separating husk from grains using the wind.
Winnowing
This method involves the separation of magnetic substances from non-magnetic substances by means of a magnet.
Magnetization or Magnetic Attraction
done to separate mixtures that contain substances mostly of different sizes. The mixture is passed through the pores of the sieve. All the smaller substances pass through easily while the bigger components of the mixture are retained.
Sieving
process by which heavier impurities present in liquid normally water settle down at the bottom of the container containing the mixture. The process takes some amount of time.
Sedimentation
Separating of mixture though pouring
Decantation
Separation of mixture through centrifugal force
Centrifugation
separate a mixture of solids containing one which sublimes and one (or more than one) which does not, by heating the mixture.
Sublimation
separates the components of a mixture on the basis of differences in particle size. It is used most often to separate a liquid (smaller particles) from a solid (larger particles).
Filtration
separates mixtures based on differences in solubility, a measure of how much solid substance remains dissolved in a given amount of a specified liquid.
the least soluble of the dissolved substances, the one that is least likely to remain in solution, usually forms crystals first, and these crystals can be removed from the remaining solution by filtration.
Crystallization
based on differences in solubility. In a typical procedure, a natural (often plant or animal) material is ground in a blender with a solvent that extracts (dissolves) compound(s) embedded in an insoluble material. This extract is separated further by the addition of a second solvent that does not dissolve in the first. After shaking in a separatory funnel, some components are extracted into the new solvent
Extraction
process that depends on the different abilities of substances to form gases.
Distillation
Used to separate miscible liquids with different but very close boiling point.
Fractional Distillation
The differing abilities of substances to adhere to the surfaces of solids can also be used to separate mixtures.
Chromatography
(literally, “the writing of colors”),
chromatography
What conclusion can be derived when the ray bends in magnetic field in the cathode ray tube experiment?
It consists of charged particles