Chem Chapt 4
Who was the most influential philosopher when it came to the subject of the composition of the natural world?
aristotle
According to the atomists, the entire physical world was made of:
atoms and void
A given chemical compound always contains the same elements in the exact same proportions by mass is the law of
definite proportions
A chemical compound is always found to be made up of the same elements combined together in different proportions by mass. true or false
false
At the time protons were discovered, it was apparent that they existed in a central nucleus. true or false
false
Atoms are the smallest particles in the universe. true or false
false
In a given type of chemical substance, the elements never combine in the same proportions by mass. true or false
false
Neutrons have neither charge nor mass. true or false
false
One piece of evidence for Dalton's atomic theory is the observation that________
a compound always has the same proportions of different elements.
The mass of a neutron is close to the mass of
a proton
For any chemical process in an isolated system in which all reactants are converted to products, the original mass of reactants must be _____ the final mass of products.
equal to
A neutral atom has equal numbers of ____ and electrons.
protons
_____ are attracted to negatively charged particles and repelled from positively charged particles
protons
In carbon dioxide, there is always 2.66 g of oxygen for every 1 g of carbon. How many grams of oxygen are in a 25.62 gram sample of carbon dioxide?
18.62
Who discovered the existence of the neutron?
Chadwick
Water is 11.19% hydrogen and 88.81% oxygen by mass. Lake Superior contains about 1.2×10^16 kg of water. What mass of hydrogen is contained in Lake Superior?
1.3 x 10^15 kg
When did John Dalton start teaching school?
12 years old
The mass ratio of H to O in water (H2O) is 1:8. What is the mass ratio of H to O in hydrogen peroxide (H2O2)?
1:16
2.56 g of hydrogen reacts completely with 20.32 g of oxygen to form X g of water. X = ___g
22.88
Two compounds of phosphorus and fluorine have the following mass ratios. Compound 1: 10.14 g fluorine for every 3.38 g phosphorus Compound 2: 8.42 g fluorine for every 4.21 g phosphorusFind the whole number ratio of masses of fluorine in compound 1 to compound 2.
3:2
A reaction between ammonia gas and chlorine gas produces ammonium chloride and nitrogen gas. A reaction of 17.0 g of ammonia with 26.6 g of chlorine gas gives off 3.50 g of nitrogen. What mass of ammonium chloride is formed in the reaction?
40.1
The molecular formula for ethane is C2H6. What is the carbon:hydrogen mass ratio for ethane?
4:1
The percent by mass of sodium in table salt (NaCl) is 39.34 %. What is the percent by mass of chlorine?
60.66%
Atoms of carbon-14 have ____ neutrons.
8
Which statement(s) is/are FALSE?
All atoms are about the same size. Protons and neutrons repel each other and position themselves far apart inside the atom.
During a chemical reaction, the law of _______ _______ states that the total mass of the products must be equal to the total mass of the reactant.
Conservation of Mass
Which of the following scientists discovered the electron?
J.J. Thomson
What is the relationship between the masses of protons and electrons?
Protons are much more massive than electrons.
What evidence from the cathode ray tube experiment support the claim that electrons have a negative charge?
The cathode ray bent away from a negatively charged plate. The cathode ray bent toward a positively charged plate.
Which of the following best describes how Thomson concluded that electrons are present in all atoms.
The charge-to-mass ratio of electrons is always the same constant, no matter which substances are used in the cathode ray tube.
Which statement(s) about neutrons is/are TRUE?
They have the same mass as protons. The major clue to their existence was extra mass in atoms that protons and electrons could not account for.
Which statement(s) about electrons is/are TRUE?
When they were first discovered, they were named "corpuscles." They have a negative charge. They have a tiny but significant mass.
What word does the ancient greek word "atomos" roughly translate to?
indivisible
The radius of an atom is closest in size to a _________ .
nanometer
Will the composition of water vary depending on its source?
no
The proportion of the mass of one element to that of another element is a mass ______
ratio
According to Dalton's atomic theory, during a chemical reaction, there is _____ of atoms.
rearrangement
Which of the following was/were used by the Greek philosophers in order to understand the world?
reason
How does the mass of the neutron compare to the mass of the proton?
slightly greater
According to Dalton, atoms cannot be ______
subdivided, created, destroyed
Which statement(s) are TRUE about protons.
they have a mass over 1800 times greater than the mass of an electron they have a positive charge
A neutron is neutrally charged. true or false
true
Electrons can be deflected by a magnetic field. true or false
true
The law of multiple proportions states that whenever the same two elements form more than one compound, the different masses of one element combine with the same mass of the other element in the ratio of small whole numbers. true or false
true
The number of protons and electrons in a neutral atom must be equal. true or false
true
Atoms of different elements can combine in simple _____ number ratios to form chemical compounds.
whole
