Unit+3+-+Atomic+Theory

Democritus and Aristotle: first discovered atoms

John Dalton: fathr of atomic theory, atoms combine in small whole number ratios

JJ thompson: plum pudding disocovered negative particles called electrons

Robert Mellikan: oil plates opposites attract

Ernest rutherford: gold foil nucleus is made of protons and electrons

James Chadwick: discovered nuetron

Neils BOhr: ground state electrons, excited state electrons

n=row on p. table I= s=0 p=1 d=2 f=3 m1= where last arow is drawn m2= 1/2 or -1/2 depending on if arrow is up or down

To do the amu you just take the percent and multiply it by .01 then multiply that by the amu. For the multiple isotopes, you do that first step for each isotope and then add all your answers together.

1) Methane is a compound in which is 75% carbon, by mass, the balance being hydrogen. If a sample of methane weighs 24 g, what mass of hydrogen does it contain? A) 2.0 g B) 4.0 g C) 6.0 g D) 8.0 g **8 x 3 = 24 so that is 75% so add another 25% or 8g** E) 18.0 g

2) Which of the following ideas was not part of Dalton's atomic theory postulates?

A) Matter consists of atoms which are indestructible. B) Atoms of an element are identical in all respects. C) Compounds consist of atoms of different elements combined in specific ratios. D) Atoms of one element cannot be converted into those of another element. E) Atoms combine to form small groups called molecules. **just look at your notes**

3) J.J. Thomson A) discovered the nucleus. B) measured the charge of the electron. **he also discovered them and they are negative** C) discovered X-Rays. D) measured the charge/mass ratio of the electron. E) invented the cathode ray tube.

4) How many protons (p), neutrons (n) and electrons (e) are there, respectively, in an atom of the chlorine-39 isotope?

A) 17 p, 17 n, 22 e B) 39 p, 38 n, 39 e C) 22 p, 17 n, 17 e D) 17 p, 39 n, 17 e E) 17 p, 22 n, 17 e **protons plus neutrons equal atomic mass, electrons are the atomic number**

5) Isotopes of an element differ in their A) chemical symbol B) atomic number C) mass number **right answer mass** D) chemical reactivity E) number of protons

6) Magnesium consists of three isotopes with the following abundances and atomic masses: 24Mg 78.70% 23.985 amu 25Mg 10.13% 24.986 26Mg 11.17% 25.983 Based on these data the atomic weight of magnesium is A) 24.99 B) 24.53 C) 24.31 **multiply the percent by .01 and take that number times the mass. do that for each and add them all up** D) 23.99 E) none of the above

7) Rutherford's experiment with alpha particle scattering by gold foil established that A) electrons have a negative charge. B) protons are 1840 times heavier than electrons. C) protons are not evenly distributed throughout an atom. D) atoms are made of protons, neutrons and electrons. E) the nucleus contains protons and neutrons. **in the notes**

8) The number of neutrons in an atom of Iodine A) 53 B) 74 **mass - atomic number** C) 126 D) 127 E) 180

9) The element antimony has an atomic weight of 121.757 amu and only two naturally occurring isotopes. One isotope has an abundance of 57.3% and an isotopic mass of 120.904 amu. What is the mass of the other isotope? A) 52.479 amu B) 121.757 amu C) 122.393 amu D) 122.610 amu E) 122.902 amu **do the mother f'in math**

10) What value or values of ml are allowable for an orbital with l = 2? A) 0 B) 2 C) -1 D) none of the above E) all of the above **1 means that it is a d so the m1 d values are -2 through 2**

11) According to the quantum-mechanical model, how many orbitals in a given atom have n = 3? A) 4 B) 7 C) 9 D) 10 E) 18

12) According to the quantum mechanical treatment of the hydrogen atom, which set of quantum numbers is not allowed? A) n = 3, l = 2, ml = 0 **it's just not possible** B) n = 3, l = 0, ml = 0 C) n = 3, l = 1, ml = 1 D) n = 3, l = 1, ml = -1 E) n = 3, l = 1, ml = 2

13) Consider this set of quantum numbers: n = 3, l = 2, ml = -1, ms = +1⁄2 The maximum number of electrons in an atom which can share the above set of quantum numbers is A) 1 B) 14 C) 3 D) 10 E) none of the above **it's just not possible**

14) An atom in its ground state contains 30 electrons. How many of these are in orbitals with l = 2? A) 2 B) 4 C) 6 D) 8 E) 10 **top row of d**

15) What are the possible values for the angular momentum quantum number (l)? A) integers from -l to 0 to +l B) 1, 2, 3, etc. C) 2, 4, 6, etc. D) +1⁄2, -1⁄2 E) integers from 0 to 3 **because mrs. wilson said so**

16) The electronic configuration of the element whose atomic number is 26 is: A) 1s2 2s2 2p6 3s2 3p6 4s0 3d8 B) 1s2 2s2 2p6 3s2 3p6 3d6 4s2 C) 1s2 2s2 2p6 3s2 3p6 4s2 3d6 **count dat out** D) 1s2 2s2 2p6 3s2 3p6 4s2 3d4 4p2 E) none of the above

17) The set of quantum numbers that correctly describes an electron in a 3p orbital is A) n = 3; l = 0; ml = 0; ms = 0 B) n = 3; l = 2; ml = -2, -1, 0, 1, or 2; ms = +1⁄2 or -1⁄2 C) n = 3; l = 1; ml = -1, 0, or 1; ms = +1⁄2 or -1⁄2 **because mrs. wilson said so** D) n = 4; l = 0; ml = -1 ,0, or 1; ms = +1⁄2 or -1⁄2 E) none of the above

18) An atom in its ground state contains 18 electrons. How many of these are in orbitals with ml = 0? A) 2 **this one** B) 4 C) 6 D) 8 E) 10

19) The configuration for the six outer electrons in ground state oxygen atoms is A) 2s3 2p3 B) 2p6 C) 2s2 2px2 2py2 D) 2s2 2px2 2py1 2pz1 **i don't know!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!** E) 2s4 2p2

Which of the following is the electron configuration for chromium, element 24? A) 1s2 2s2 2p6 3s2 3p6 4s2 B) 1s2 2s2 2p6 3s2 3p6 4s2 3d4 **this one** C) 1s2 2s2 2p6 3s2 3p6 3d6 D) 1s2 2s2 2p6 3s2 3p6 4s1 3d5 E) 1s2 2s2 2p6 3s2 3p6 4s2 3d1 3d1