Science unit 1 Flashcards
What is matter
matter is anything that takes up space
What are the two types of pure substances
elements and compounds
What is an element
only one type of atom
What is a compound
two or more types of atoms; e.x. H2O
What is a mixture
a substance that contains more than one type of particle
What is a heterogeneous mixture
(mechanical mixture) A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. (you can see the different components)
What is homogeneous mixture
(solutions): A homogeneous mixture is a mixture in which the composition is uniform and looks like one throughout the mixture.
What is a alloy
an alloy is a type of solution composed of two or more metals
examples of alloys
-Bronze=copper+tin
-Steel=Iron+carbon
-Brass=Copper+zink
What are physical properties
a characteristic of a substance that can be determined using observations we make
what is a qualitative observation
observations made using our five senses (sight, smell, taste, touch, and sound)
What is a quantitative obstervation
observations made by measuring and has a numerical value
What is lustre
shininess of an object
What is optical clarity
the ability to allow light through (i.e. transparent, translucent, opaque)
What is brittleness
tendency to break/crack
What is viscosity
the ability of a substance flow or pour readily
What is hardness
the ability to be scratched by another substance
what is malleability
the ability to be hammered into a thinner sheet or molded
What is ductility
the ability to be drawn (pulled) into a wire
what is electrical condutivity
the ability to conduct electricity
What are physical changes
a change in a substance that does not alter its composition (The particles in a physical change do not change); usually reversible
What are characteristic physical properties
characteristic physical properties can be used to identify a substance.
These include: solubility, freezing point, melting point, boiling point, and density.
what is freezing point
temperature a substance turns from liquid to solid
what is melting point
temperature a substance turns from solid to liquid (same temperature as freezing point)
what is boiling point
temperature a substance turns from liquid to gas
what is density
the degree of compactness of a substance. (d=m/v)
what are chemical properties
a property of a substance that describes its ability to undergo changes to its composition to produce one or more new substances
Examples of chemical properties
-Flammability - ability to burn at room temperature
-Combustibility - ability to burn at a raised temperature
-Toxicity - ability to poison
-Corrosivity - ability to corrode or eat away
What is a chemical change
a change in the composition of a substance that results in one or more new substances
What are the five clues of chemical chanage
-Colour change
-Change in odour
-Bubbles of gas form
-Precipitate formed (solid that separates from solution)
-Change in temperature/ light produced
(at least one change must occur to consider it a chemical change)
Who is Democritus
A Greek philosopher 400 BCE propose matter, was composed of small indivisible blocks of various shapes, and sizes. Named this particle the atom which means “cannot cut”
Who was Aristotle
Greek philosopher 450 BCE. Rejected the concept of the atom supported an earlier theory of all matter is made up of four substances: earth, water, air, and fire.
Who was John dalton
John Dalton, 1807. Proposed the “ billiard ball model”. His main ideas were
1 all matter is made up of atoms
2 Atoms of an element are identical
3 different elements have different atoms
4 Adams can be rearranged to form new substances, but can’t be created or destroyed.
Who was JJ Thompson
JJ Thompson 1897. Discovered the electron using cathode ray tube experiment. Adams contain negatively charge particles called electrons, embedded in a positively charge sphere. Called it the plum pudding model.
Who was Ernest Rutherford
Ernest Rutherford, 1909, 1920. Discovered the nucleus in 1909, using his gold foil experiment. Nucleus is very small, but dense centre of the atom surrounded by empty space. Nucleus is surrounded by electrons and is positively charged. Discovered protons in 1920.
What was the gold foil experiment
Fire positively charged particles at a piece of gold foil. Some particles bounce right back. So Rutherford concluded that there were very small, but dense center of the atom that must be positively charge called the nucleus
Who was James Chadwick
James Chadwick, 1932. Proposed that the nucleus must contain neutral particles called neutrons that make up portions of the atoms mass. Determined the mass of a proton equals the mass of a neutron.
Who was Neil’s Bohr
Neil Bohr , 1913. Conducted experiments with the hydrogen atoms and the light it produce when electricity runs to it. Bohr propose the following: electrons orbit, the nucleus, orbits can hold surgeon numbers of electrons, the further and electron is from the nucleus the more energy, electrons return back to their original orbits and release energy as light.
Why do elements form compounds
Adams are not stable if they’re highest i.e. last shells do not have the maximum number of electrons.
