electron
Which of the 3 subatomic particles – proton, electron, or neutron – has the least mass?
isotopes
Most calcium atoms have an atomic number of 20 and a mass number of 40, but some calcium atoms have a mass number of 48. What work could you use to describe these 2 kinds of calcium atoms?
energy is either gained or released
What can scientists measure to provide evidence that electrons can move from one energy level to another?
shows likely or possible locations of electrons
How does the electron cloud model of the atom represent the locations of electrons in atoms?
electrons change from excited state to ground state
How does the state of atoms in a neon light change when light is emitted?
Selenium is a nonmetal. Rubidium is a metal.
Selenium has 6 valence electrons, while rubidium has 1 valence electron. Identify each element as a metal or a nonmetal.
chlorine
The elements silicon and chlorine are both in Period 3. Which is the more reactive element?
it’s not highly reactive under ordinary conditions
Sulfur is often found in nature as an element, not combined with other elements in a compound. What does this fact tell you about the reactivity of sulfur?
period; periods go across like rows
Suppose you are looking at elements in the periodic table in this order: element 23, element 24, element 25, element 26, and so on. Is this an example of a period or a group/family?
the number of valence electrons
What determines an element’s chemical properties?
36 is the atomic number or the number of protons in the atom of krypton; 83.80 is the atomic mass or the weighted average of the atomic masses of krypton
On the periodic table, there are 2 numbers in the block for the element krypton, Kr: 36 and 83.80. What are each of these numbers, and what do they represent?
metalloids
Boron, silicon, germanium, and arsenic are elements that have properties that fall between those of metals and nonmetals. What common label could you apply to these elements?
cadmium
Period 5 of the periodic table begins with element 37 and ends with element 54. Consider the following elements from row 5: strontium, cadmium, iodine. Which of these elements is most likely to be a transition metal?
strontium
Among the alkaline earth metals in Group 2A, which is more reactive – beryllium or strontium?
sodium is the alkali metal and chlorine is the halogen
Sodium chloride is a compound of sodium and chlorine. Which of these elements is the alkali metal, and which is the halogen?
the heated filament will react with the oxygen in the air but now with the argon, which is a noble gas and hardly ever reacts
Why is argon gas used instead of air in light bulbs that contain a filament that is heated to glowing?
when the fireworks explode, the electrons go to the excited state and move up energy levels; when the electrons go to the ground state, some of the energy is released as visible light; the colors vary because each element has a different set of energy levels
Explain what the colors in a fireworks display reveal about the movement of electrons in atoms.
you could see which piece conducts an electric current or which piece is a better conductor of heat
In science lab, your teacher gives you two small pieces of matter and tells you that one piece is a metal and one is a nonmetal. Without changing the size or shape of the pieces, how could you test them to determine which is the metal?
It’s be easier to discover something with a positive charge than with no charge.
Inferring: why do you think the proton was discovered before the neutron?
Beryllium, Carbon, Nitrogen, Fluorine
Using tables and graphs: which of the elements shown in figure 5-2 are in the same period? (look at the figure)
vanadium is a transition metal; helium is a noble gas
Classifying: which element in figure 5-2 is a transition metal? Which is a noble gas? (look at figure 5-2 on paper)
fluorine and Iodine because they’re both in the same group/family
Using tables and graphs: which elements in figure 5-2 have the same number of valence electrons? How do you know? (look at the figure)
Both are metals; different numbers of valence electrons, beryllium is an earth metal
Comparing and Contrasting: based on what you know about elements and the periodic table, compare and contrast the elements beryllium, iodine, which are shown in figure 5-2. (look at figure)
atomic number is 12, v. electron # is 2, and it represents beryllium
Inferring: find the block labeled ‘?’ in figure 5-2. Predict the properties of this element. What’s the atomic number? How many v. electrons? Which element in the figure does it most resemble? (look at figure)
metals
Classify the elements in figure 5-3 as metals, metalloids, or nonmetals. Explain your answer. (look at figure)
rubidium = alkali metal; most reactive
identify the most reactive element shown in figure 5-3. (see figure)
similar properties because they’re in similar groups
explain why knowing the properties of K, Ca, Sc, and Ti would allow you to predict the properties of Rb, Sr, Y, and Zr. (see figure)
atomic #’s; importance = to classify the different elements
what do the numbers in the boxes in figure 5-3 represent? What is the importance of these numbers?
Group 1A has similar properties and same number of valence electrons. same with Group 2A.
describe ways in which the elements in group 1A are similar. then describe how 2A elements are similar. then describe the differences
