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Chemistry Chapter 3
| Question | Answer |
|---|---|
| 1) What is the total number of valence electrons in an atom in the Alkali Earth Metals Group? | 2 |
| 2) A Ca2+ ion differs from a Ca0 atom in that the Ca2+ ion has | Fewer Electrons |
| 3) Which particles are referred to as corpuscles by Thomson | Electrons |
| 4) What is the mass number of an atom that contains 19 protons, 19 electrons, and 20 neutrons? | 39 |
| 5) What term refers to the path of an atom where an electron is most likely to be found according to Bohr? | Orbit |
| 6) The nucleus of an atom consists of 8 protons and 6 neutrons. The total number of electrons present in a neutral atom of this element is | 8 |
| 7) What is the maximum number of electrons that can occupy the third orbit (according to Bohr)? | 8 |
| 8) Atoms of 16O, 17O, and 18O have the same number of | Protons. but a different number of Neutrons |
| 9) All atoms of an element have the same | Atomic Number |
| 10) The atomic number is always equal to the total number of | Protons in the Nucleus |
| How many protons are in the nucleus of an atom of beryllium? | 4 |
| 12) Which subatomic particle is negative? | Electron |
| 13) Which of the following particles has the least mass? | Electron |
| A sample of element X contains 90% X-35 atoms, 8.0% X-37 atoms, and 2.0% X-38 atoms. The average atomic mass will be closest to which value? | 35 |
| 15) What is the total number of electrons in an Mg+2 ion? | 10 |
| The atomic mass of an element is defined as the weighted average mass of that element’s | Naturally Occurring Isotopes |
| 19) Compared to the entire atom, the nucleus of the atom is | Smaller and Contains most of the atoms mass |
| 20) What is the nuclear charge in an atom of boron? | +5 |
| 21) What subatomic particle was discovered in the cathode ray tube experiment? | Electron |
| 22) Which of the following is NOT part of Dalton’s atomic theory? | Atoms are in constant motion |
| 23) How many of the following did Dalton NOT discuss in his atomic theory? Isotopes ion protons electrons neutrons | 5 |
| 24) The law of constant composition applies to | Compounds |
| 25) The fundamental “particle” of a chemical element according to Dalton’s theory is the | Atom |
| 26) The first scientist to show that atoms emit tiny negative particles was | Thomson |
| 27) The scientist whose alpha-particle scattering experiment led him to conclude that the nucleus of an atom contains a dense center of positive charge is | Rutherford |
| Most of the alpha particles passed through the gold foil undeflected. What conclusion was made about the structure of the atom based on this observation? | Most of the atom is empty space in which electrons zoom around |
| b) A few of the alpha particles were deflected back at the source and toward the screen. What did this observation reveal about the structure of the atom? | The atom has a small dense positive core containing protons and neutrons |
| An element has two isotopes. 90% of the isotopes have a mass number of 20 amu, while 10% have a mass number of 22 amu. Calculate the atomic mass of the element. Show all work with units. | ( 20 * .90) + ( 22 * .10) = 20.2 amu |
| 31) How can you tell the difference between an atom and an ion? | An atom has an equal number of protons (+) and electrons (-). An ion has either fewer or more electrons than protons. (A positive ion has fewer electrons and a negative ion has more electrons) |
| 32) What is the octet rule? | An atom will either lose or gain electrons to achieve 8 outer (valence) electrons. |
| 33) Why do noble gases not typically form ions? | They already have 8 outer electrons |