FALSE! 1 TRUE or FALSE Electrons have a positive charge. Electrons have a NEGATIVE charge. 1

TRUE or FALSE All atoms of the same element contain the same number of neutrons. FALSE! Protons are what determine an element is. Neutrons can change in isotopes. 2

FALSE! 3 TRUE or FALSE Protons have no electrical charge. Neutrons have no electrical charge. Protons have a positive charge. 3

TRUE or FALSE The atomic number of an element is the number of protons and neutrons in the nucleus. FALSE! The mass number of an element is the number of protons and neutrons in the nucleus. 4

TRUE or FALSE The mass number is an average of the masses of all naturally occurring isotopes of an element. FALSE! The atomic mass is an average of the masses of all naturally occurring isotopes of an element. 5

B. Neutron C. Electron D. Nucleus 6 The discovery of which particle proved that the atom is not indivisable? A. Proton B. Neutron C. Electron D. Nucleus 6

Hint: Atomic Number = Number of Protons How many protons does an atom with an atomic number of 23 and a mass number of 51 have? A. 23 B. 28 C. 51 D. 74 Hint: Atomic Number = Number of Protons 7

In Rutherford’s gold – foil experiment, Rutherford concluded that the atom is mostly empty space with a small, massive, positively charged center because: Most of the particles passed straight through the foil Some particles were slightly deflected A few particles bounced straight back All of the above 8

Which of the following determines the identity of an element? A. Atomic Number B. Mass Number C. Atomic Mass D. Overall Charge 9

Isotopes exist because atoms of the same element can have different numbers of A. Protons B. Neutrons C. Electrons D. None of the Above 10

What force holds electrons in atoms? Electromagnetic force. The proton is positive and the electron is negative , so they are attracted to each other. 11

12 In two or three sentences describe Thomson’s plum pudding theory. Thomson proposed that electrons were located throughout an atom like plums in a pudding. . 12

Caluculate the atomic mass of gallium, which consists of 60% gallium – 69, 40% gallium – 71. .60 x 69 = 41.4 + .40 x 71 = 28.4 69.8 13

Calculate the number of protons, neutrons, and electrons in an atom of zinconium-90 that has no overall charge and an atomic number of 40. Atomic Number = Number of Protons Protons = 40 Atomic Weight = Protons + Neutrons Neutrons = Atomic Weight – Protons 50 = 90 - 40 Electrons = 40 (Same as Protons, since no overall charge) 14

Nucleus contains protons and neutrons. ATOM Positive (+) Negative (-) Proton Electron Neutron Neutral (=) Atomic Number Atomic # = # of Protons Mass Number Isotopes Mass # = Protons + Neutrons Nucleus Isotopes have same number of protons, different number of neutrons. Nucleus contains protons and neutrons. 15

Particle accelerators, such as the Hadron Collider, are devices that speed up charged particles in order to smash them together. Scientist use these devices to make atoms. How can scientists determine whether the atoms formed are a new element or a new isotope of a known element? If the number of protons stays the same, but number of neutrons changes, you would have a new isotope. If the number of protons changes, you would have split the atom into a new element. http://www.youtube.com/watch?v=qQNpucos9wc http://www.youtube.com/watch?v=RIg1Vh7uPyw&list=TL9liUotc3avVG69w_AB1a0zk9sCfDLWVc&safe=active 16

John Dalton made a number of statements about atoms that are now known to be incorrect. Why do you think atomic theory is still found in science textbooks? Dalton’s atomic theory was the first one based on experimental evidence. It helps show how a theory develops as new information is discovered. 17

If scientists had tried to repeat Thomson’s experiment and found that they could not, would Thomson’s conclusion still have been valid? No, the results of an experiment must be repeatable to be considered valid. 18

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