Chemistry Chapter 3 Study Guide
State two revised principals from Dalton's atomic theory.
1. Atoms are divisible into smaller, subatomic particles. 2. A given element can have atoms with different masses, called isotopes.
The formation of water according to the equation 2H2 + O2 ->2H2O shows that 2 molecules (made of 4 atoms) of hydrogen and 1 molecule (made of 2 atoms) of oxygen produce 2 molecules of water. The total mass of the product, water, is equal to the s of the masses of each of the reactants, hydrogen and oxygen. What parts of Dalton's atomic theory are illustrated by this reaction? What law does this reaction illustrate?
1. Atoms cannot be subdivided, created, or destroyed. 2. Atoms of different elements combine in simple, whole-number ratios to form compounds. This reaction also illustrates the Law of Conservation of Mass.
Where is the electron located? What is its charge? What is its relative mass?
It is located far outside the nucleus, it has a negative charge, it's relative mass is 1/1837 amu.
Where is a proton located? What is its charge? What is its relative mass?
It is located in the nucleus. It is positively charged. It's actual mass is 1.673 x 10-27 kg. a
Where is the neutron located? What is its charge? What is its mass?
It's located in the nucleus, it has a neutral charge, it's mass is 1.675 x 10-27kg. A
A sample of baking soda, NaHCO3 always contains 27.37% by mass of sodium, 1.20% of hydrogen, 14.30% of carbon, and 57.14% of oxygen. Which law does this data illustrate?
The Law of Definite Proportions: the fact that a chemical compound contains exactly the same proportions by mass regardless of the size or sample of the source of the compound.
How could the electrons produced in a cathode-ray tube filled with neon gas compare with the electrons produced in a cathode-ray tube filled with chlorine gas?
The electrons produced from neon gas and chlorine gas would behave in the same way because electrons do not differ from element to element.
Explain the difference between the mass number and the atomic number.
The mass number is the number of protons plus the number of neutrons. The atomic number is the amount of protons.
A cathode ray produced in a gas-filled tube is deflected by a magnetic field. A wire carrying an electric current can be pulled by a magnetic field. A cathode ray is deflected away from a negatively charged object. What property of the cathode ray is shown by these phenomena?
The particles that compose cathode rays are negativity charged.
a. Is an atom positively charged, negatively charged, or neutral? b. Explain how an atom can exist in this state.
a. Neutral b. Atoms consist of a positively charged nucleus, made up of protons and neutrons, that is surrounded by a negatively charged electron cloud.
The smallest unit of an element that can exist either alone or in molecules containing the same or different elements is the _____.
atom
In cathode-ray tubes, the cathode ray is emitted from the negative electrode, which is called the _____.
cathode
The subatomic particles that are least massive and most massive, respectively, are the _____ and _____.
electron and neutron
A nuclear particle that has no electrical charge is called a(n) _____.
neutron
A positively charged particle found in the nucleus is called a(n) _____.
proton
