QUIZ 1! Flashcards
What did Thales think was the universal element? What did he contribute?
water
argued that Earth floated on water
What did Anaximander think was the universal element? What did he contribute?
earth
focused on opposites found in nature
argued for “Apeiron”
What did Anaximenes think was the universal element?
air
used observations of rarefaction and condensation to conclude that air is the primary substance
What did Heraclitus think was the universal element?
fire
believed in constant change and transformation
death of fire is birth of everything else
What is meant by the term “atomism” as a philosophy?
nature consists of “atom” and “void”
What did Empedocles contribute?
material pluralism
air, earth, water, fire
What contributions did Democritus and Leucippus make to atomism?
originated atomism, thought stuff was formed when atoms fall into the void and are tangled with each other
What were five postulates of Leucippus and Democritus’ atomism?
all matter is made of atoms the volume in between atoms is empty space atoms are always in constant motion there are infinite numbers of atoms atoms vary in shape and size
Why was the atomism of Leucippus and Democritus relatively obscure until the early 1800’s?
it wasn’t agreed upon by influential philosophers, but by 1800s there was enough empirical evidence
Why were Greek philosophers so interested in material monism rather than pluralism?
sorting the world into elements was simpler and easier to understand
Who was Aristotle and what did he contribute?
proposed existence of 5th element (aether) found in celestial regions and heavenly bodies
What contributions did Leucippus make to the development of the atomic model?
theorized the principle of the atom as a fundamental basis of nature
What contributions did Democritus make to the development of the atomic model?
spread the atomist view of nature into the academic community
What contributions did Antoine Lavoisier make to the development of the atomic model?
- Law of Conservation of Mass
- mass is neither created nor destroyed
wrote first extensive list of elements
What contributions did Joseph Louis Proust make to the development of the atomic model?
Law of Definite Proportions
- in a pure compound, elements are always present in the same proportion by mass
What contributions did John Dalton make to the development of the atomic model?
Law of Multiple Proportions
- ratio of mass of one element that combines a fixed mass of a second element to make 2 different compounds
What did John Joseph Thomson contribute to the development of the atomic model?
realized that atoms have a positive and negative component
What did Ernest Rutherford contribute to the development of the atomic model?
determined that the positive charge of an atom is concentrated into a small nucleus and negatively charged electrons are in a larger volume of space around the nucleus
What did Neils Bohr contribute to the development of the atomic model?
he created a model that placed electrons in orbits around the nucleus
What did Louis de Brogile contribute to the development of the atomic model?
proposed that all matter has wave properties, especially electrons
showed that electrons don’t orbit the atom
What did Erwin Schrodinger contribute to the development of the atomic model?
proposed a new model with the electron in a region of space called orbital
What are the 5 postulates of John Dalton’s atomic theory?
all elements are made of atoms
atoms of a given element are identical
atoms can’t be created, destroyed, or subdivided
atoms combine in simple whole number ratios to form chemical compounds
atoms combine, separate, and rearrange in chemical reactions
How are the atomic theories of Leucippus/ Democritus and John Dalton alike?
everything is made of atoms
atoms in different elements are different
they vary by shape and size
Why was John Dalton’s atomic theory more quickly accepted by his contemporaries than was the atomic theory of Leucippus and Democritus?
supported his ideas with empirical evidence developed by himself and others
What is the meaning of the term “Subatomic particle”?
A subatomic particle is a particle that is smaller than an atom and is usually a constituent particle of
most atoms.
Who is the first person credited with first characterizing the electron?
J.J. Thomson
What are the properties of an electron?
subatomic particles with a negative charge.
mass of 9.109 x 10-28 grams.
not located in the nucleus of an atom but are instead located in the electron cloud.
Who is the first person credited with characterizing the proton?
Ernest Rutherford
What are the properties of a proton?
subatomic particles having a positive charge.
mass of 1.673 x 10-24 grams.
located in the nucleus of an atom.
nucleons because they are located in the nucleus of an atom.
Who is the first person credited with characterizing the neutron?
James Chadwick
What are the properties of a neutron?
subatomic particles that do not have an electrical charge.
mass of 1.675 x 10-24 grams.
located in the nucleus of an atom.
nucleons because they are located in the nucleus of an atom.
Who is the first person credited with characterizing the nucleus of an atom?
Ernest Rutherford
What are the properties of the nucleus of an atom?
contains all of an atom’s protons and neutrons.
very small and dense when compared to the rest of the atom.
always positively charged.
contains almost all of an atom’s mass.
Why does the nucleus of every atom have an overall positive charge?
The nucleus of an atom is always positively charged because of the positively charged protons
within it. The other particles located in the nucleus – the neutrons – do not have an electrical charge
and therefore do not affect the overall charge of the nucleus.
Why is almost all the mass of an atom located in its nucleus?
The nucleus of an atom contains almost all of the atoms mass because the two particles found
within it – the protons and the neutrons – are each 1837 times and 1839 times, respectively, more
massive than the electrons in the electron cloud of the atom.
What is the meaning of the term “nucleon”?
any subatomic particle found in the nucleus of an atom. Since all atomic nucleuses,
other than the simplest form of hydrogen, contain protons and neutrons, those particles; that is
protons and neutrons, are considered to be nucleons.
What are the properties of the “electron cloud” in an atom?
a relatively large region of the atom when compared to the nucleus.
mostly empty space in which the electrons move about.
the electrons – are negatively charged, the
electron cloud itself is considered to be negatively charged.
Why is an atom always electrically neutral?
for every proton located in its nucleus,
there is a corresponding electron located in its electron cloud.
Since the neutrons do not have an electrical charge, they have no effect on the overall charge of
the atom.
