Chapter 3 Review
What is a compound? give examples
A compounds is a pure substance that is composed of two or more elements held together by chemical bonds; examples, water carbon dioxide
For each o fate following simple ions, indicate the number of protons and electrons the ion contains a. K+ c. Br- e. Na +
A. Protons- 19 electrons-18 C. protons- 35 electrons- 36 E. protons Na-11 electrons 10
Write the name and atomic number for each of the following elements a. Si b. C c. F d. Be e. O f. Cr
A. silicon 14 B. Carbon 6 C. Fluorine 9 D. Beryllium 4 E. Oxygen 8 F. Chromium 24
Are most elements found in nature in the elemental or in the combined form? Why? Name several elements that are usually found in the elemental form.
Elements mostly found in combined form; elements found in elemental form Gold and Silver
Write the name and chemical symbol for each of the following elements a. 36 b. 92 c. 15 d. 79 e. 29 f. 8
a. Krypton Kr b. U Uranium c. P Phosphorus d. Au gold e. Cu copper f. O oxygen
Not true about a carbon 14-atom contain 6 protons contains 6 electrons 6 neutrons
6 neutrons
How many of these occur naturally and how many are man-made?
88 occur naturally and 26 man-made
State as many points as you can of Dalton's atomic theory. Explain in your own words each point
All elements are composed of atoms, which are indivisible and indestructible Atoms of the same element are exactly the same, and atoms of different elements are different Compounds are formed by joining atoms of two or more elements in fixed proportions Atoms are indivisible in chemical processes (can't break apart of chemical reaction
How are ions formed from atoms?
An ion is formed when an atom gains or loses an electron
Can an ionic compound consist only of cations or anions but not both? Explain.
An ionic compound must consist of both a cation and an anion because if it didn't have one it would't be an ionic compound
What are isotopes?
Atoms with the same number of protons but different number of neutrons
The element chlorine belongs to which of the following groups
Halogens
write the name and atomic number for each of the following elements A. He B. B C. Se D. Ba E. P F. Sr
Helium 2 Boron 5 Selenium 34 Barium 56 Phosphorous 15 Strontium 38
Do isolated atoms form ions spontaneously? Explain
Isolated atoms don't form ions on their own, but gain or lose electrons.
Which general area of the periodic table contains the metallic elements and the nonmetallic elements?
Metallic elements are found in the left side of the table and non-metallic elements on the right upper side.
Write the symbol and atomic number for each of the following elements magnesium, tin, lead, sodium, hydrogen, chlorine and silver
Mg-12 Tin-50 Lead-82 Na-11 H-1 Cl-17 Silver-47
Most abundant element by mass in the earth's crust and in the human body
Oxygen
Which elements are most abundant on the Earth?
Oxygen, silicon, aluminum and other
Write the name and chemical symbol for each of the following elements a. 19 b. 12 c. 1 d. 6 e. 82 f. 2
Potassium K Magnesium Mg Hydrogen H carbon C Lead Pb Helium He
Write the symbol and atomic number for each of the following elements: Potassium, calcium, bromine, neon, aluminum, gold, mercury, and iodine
Potassium K 19 Calcium Ca 20 Bromine Br 35 Neon Ne 10 Aluminum Al 13 Gold Au 79 Mercury Hg 80 Iodine I 53
What are the three fundamental particles that compose all atoms? Indicate the electrical charge and relative mass of each of these particles. Where is each type of particle found in the atom?
Proton, Electron, Neutron . Proton and Neutron found in nucleus. Electron orbits nucleus. Proton is positive charge. Electron is negative charge. Neutron has no charge.
Using the ions indicated in Question 8 write the formulas and give the names for all possible simple ionic compounds involving these ions
RbH, RbCl, Rb2O, FeH2, FeCl2, FeO, AlH3, AlCl3, Al2O3
Explain Rutherford's reasoning in developing his model
Rutherford developed his model as a result of an experiment in which alpha particles were fired at a thin sheet of gold foil. if he was right the particles would have passed straight through the foil but some particles deflected, Rutherford concluded there must be a dense positive charged nucleus at the center of the atom
Describe the points of Rutherford's model of the nuclear atom and how he tested this model? Based on Rutherford's experiments how did Rutherford envision the structure of the atom? How did Rutherford's model for atomic structure differ from Thomson's "plum pudding model" ?
Rutherford's experiment involved shooting a beam of particles at metal foil. According to the plum pudding model of the atom most of these positive charged particles should have passed right through the foil. Rutherford found out that some particles deflected. Rutherford's experiment disproved the "plum pudding" model for the atom and envision the atom as a sphere of positive and negative charged scattered through the atom.
Do the isotopes of a given element have the same chemical and physical properties? Explain.
The isotopes of a given element have the same chemical since the chemical properties of an atom are a function of the electrons in the atom but not the same physical properties because of the difference in the mass of the isotopes
What is meant by the law of constant composition for compounds and why is this law so important to our study of chemistry?
The law of constant composition is a result of the fact that a given compound always contain the same types and number of each atom.
How might the results of Rutherford's experiment have been different if he had used foil, rather than foil?
The nucleus of an aluminum atom would have made a smaller target , more alpha particles would had passed through the foil without showing any deflection
Why do the symbols for some elements seem to bear no relationship to the name for the elements give examples explain
The symbols for some elements may refer to an archaic name for the element or the element's name in modern language other than english examples : Na Sodium Natrium; K potassium Kalium
Since ionic compounds are made up electrically charged particles, why doesn't such a compound have an overall electric charge?
There is no electrical charge, the total number of positive charges is balanced by an equal number of negative charges
Compare Rutherford's model of the atom to Thomson's model
Thomson's model of the atom consisted of electrons floating in positive charge;Rutherford's model of the atom consisted of a dense positively charged nucleus at the center of the atom, with the majority of the atom being empty space, where the electrons occupied
For each of the following simple ions, indicate the number of protons and electrons the ion contains a. H+ b. N 3- c. F - 9
a 1p 0 e b 7p 10 e c 9 p 10 e
which of the following is most likely to form a cation
a metal
In terms of subatomic particles how is a cation related to the atom from which it is formed? An anion? Does the nucleus of an atom change when an atom is converted into an ion?
a positive ion forms an atoms or molecule loses one or more of its electrons Na (atom) >> Na + (ion) + e- ions contain the same number of protons and neutrons
What is an element?
a substance that cannot be decomposed into a simpler substances by chemical or physical means it consists of atoms all having the same atomic number
What simple ion does each of the following elements most commonly form? a. Ag b. Al c. Br d. K e. S f. Ca
a. 1+ b 3+ c 1- d 1+ e 2- f 2+
What simple ion does each of the following elements most commonly form? a. Mg b. F c. Ba d. Na e. O f. Cl
a. 2+ b. 1- c. 2+ d. 1+ e. 2- f. 1-
Indicate the number of protons, neutrons, and electrons in isolated atoms having the following nuclear symbols a. 4He 2 b. 37Cl 17 c. 40 Ca 20
a. N-2 P-2 E-2 b. N-20 P-17-E-17 c. N-20 P-20 E-20
Indicate the number of protons, neutrons, and electrons in isolated atoms having the following nuclear symbols a. 19 F- 9 b 24 Mg 2+ 12 c. 56 Fe 3+ 26
a. n-10 p-9 e-10 b. n-12 p-12- e-10 c. n-30 p-26 e-23
For each of the following simple ions, indicate the number of protons and electrons the ion contains a. Rb + b. Fe 2+ c. H- d. Al 3+ e.Cl- f. O 2-
a. p 37 e 36 b. p 26 e 24 c. p 1 e 2 d. p 13 e 10 e. p 17 e 18 f. p 8 e 10
Indicate the number of protons, neutrons, and electrons in isolated atoms having the following nuclear symbols: a. 79 Br 35 b. 238U 92 c. 1H 1
a. p/e = 35 n= 44 b. p/e= 92 n=146 c. p/e=1 n=0
ion
atom with a charge
the identity of an element is determined by it
atomic number
Which of the following is not part of Dalton's atomic theory
atoms are in constant motion
What are ions?
atoms with a charge
isotopes
atoms with same number of protons but different number of neutrons
nucleus
dense positively charged center of atom
anion
negatively charged ion
Electron
negatively charged subatomic particle
Describe the periodic table of the elements. How are the elements arranged in the table? What significance is there in the way the elements are arranged into vertical groups? How can the periodic table be used to predict what ion an element's atoms will form?
elements are in order of increasing atomic number, placed with similar chemical properties into the same group. the periodic table is arranged with the elements in the same vertical column having similar chemical properties
Which pair contains an element that is NOT diatomic?
hydrogen and helium
What are some general physical properties of ionic compounds such as sodium chloride? How do we know that substances such as sodium chloride consist of positively and negatively charged particles?
ionic compounds are hard solids with high melting and boiling points. When sodium chloride is dissolved in water or melted it conducts electrical currents.
To what do the atomic number and the mass number of an isotope refer?
isotopes have the same atomic number but different mass number; the different isotopes are indicated by the form of A X Z Z is the atomic number a is the Atomic mass X is the element example 79 Br/35
How many elements are presently known?
more than 110 elements
atomic number
number of protons in the nucleus of an atom
To what do the terms cation and anion refer?
positive charged ions are called cations and negative ions are called anions
cation
positively charged ion
proton
positively charged subatomic particle
neutron
subatomic particle with zero charge
mass number
sum of the number of protons and the number of neutrons in the nucleus of an atom
What is meant by the term nuclear atom?
the atom having a dense center of positive charge (the nucleus) and electrons moving around the outside
Which of the subatomic particles is responsible for the chemical behavior of a given type of atom? Why?
the number and arrangement of the electrons in an atom is responsible for the chemical behavior of the atom; the electrons are found in the space occupied by an atom from just outside the nucleus, when two atoms approach each other, the electrons from one atom interact with the electrons on the other, however the the nucleus is to small the nuclei of the atoms don't interact
an ion always contains
unequal numbers of protons and electrons
