Atoms
What number tells you the number of protons?
Atomic Number
How does the atomic number change from left to right across the periodic table?
increases by one
Which group on the periodic table has the least reactive elements?
Noble gases (group 18)
What element has the symbol Xe?
Xenon
How do you figure out the number of neutrons in an atom?
Subtract the atomic number from the mass number
How does atomic mass change down a group?
increases
Which group on the periodic table has the most reactive metals?
alkali metals (group 1)
What element has 17 electrons?
Chlorine
Use its location on the periodic table to determine the electron distribution for phosphorus.
3rd period, group 15, so it has 3 shells and 5 valence electrons: 2, 8, 5
How do you find an element's mass number?
Add the number of neutrons and the number of protons together
How does the metallic nature of elements change from left to right across the periodic table?
decreases - the elements go from metals to metalloids to nonmetals
Which group on the periodic table is the most reactive nonmetal group?
halogen (group 17)
What element has 2 valence electrons and 6 energy levels?
Barium
Would barium gain or lose electrons to form an ion? How many electrons?
Barium loses two electrons. It would lose its two valence electrons.
Why do isotopes of an atom have different mass numbers? Example C-12 and C-14
Isotopes of the same element have different masses because they have different numbers of neutrons. The protons and electrons are the same for all the isotopes.
What causes the increase in size (radius) as you go down a group on the periodic table?
Every period adds an electron shell. This increases the atom's volume.
Which group on the periodic table has reactive metals that are used in fireworks?
Alkaline Earth Metals (group 2)
Why isn't an element with an electron pattern of 2, 8, 8 reactive?
Its outer shell is full, so it doesn't form an ion (normally won't gain or lose electrons)
Why is the atomic mass for an element a decimal when the mass number is not?
Atomic mass is a decimal because it is the weighted average of the isotopes of the element. Mass number is the sum of protons and neutrons in a single atom, so it is always a whole number.
What is the source of the volume of an atom?
Electrons repelling each other outside the nucleus
Which group contains the least reactive metals that are used in industry (ie construction).
transition metals (groups 3-12)
Which element has 7 valence electrons and electrons in 3 energy levels?
Chlorine
Explain how to find the atomic mass of oxygen with two isotopes: O-15 10% and O-16 90%
Multiply the percentage by the mass number for each isotope, then add the resulting masses together.