Category 1
What is an electron?
Negatively charged particles.
What is a covalent bond?
Sharing electrons
An element is in period 3 and group 17. What can you predict about it?
a)It has 3 energy levels and 7 valence electrons.
b)It has 17 energy levels and 3 valence electrons.
c) It is a noble gas.
d)It has 3 protons.
a)It has 3 energy levels and 7 valence electrons.
What is a radioactive isotope?
A radioactive isotope is an unstable form of an element that gives off radiation as it breaks down.
Two elements are in the same period but different group. What is the same about them?
Same number of energy levels.
True or False
Electrons determine chemical behavior.
True.
Atoms share electrons to
a) Lose energy
b) Become stable
c) Gain mass
d)Form ions
b) Become stable
Why do elements in the same group often react in similar ways?
They have the same number of valence electrons, so they gain,lose, or share electrons in similar ways.
Carbon-14 is useful for dating old objects because it
a) Never changes
b) Breaks down at a steady rate
c) Has no neutrons
d) Is always stable
b) Breaks down at a steady rate
An atom has 12 protons,12 neutrons, and 10 electrons. What is true?
a) It is neutral
b) It is a negative ion
c) It is a positive ion
d) It changed into another element.
c) It is a positive ion
Why are valence electrons important?
They control bonding and reactions.
True or False
Covalent bonds occur between nonmetals.
True
Which element would most likely behave like Sodium?
a) Magnesium
b) Potassium
c) Neon
d) Chlorine
b) Potassium
Why can radioactive isotope be useful in medicine even though radiation can be dangerous?
Small, controlled amounts can be used to find or treat diseases, but too much radiation can harm cells.
What happens if an atom does not reach a stable outer shell?
It remains reactive and keeps trying to bond.
An atom with 7 valence electrons is
a) stable
b) unstable
c) Metal
d)Neutral
b) unstable
Which is stable?
a) 1 valence
b) 8 valence
c) 3 valence
d) 5 valence
b) 8 valence
True or False
An element's period number tells how many valence electrons it has.
False. The period tells the number of energy levels.
Why are electrons important if they don't define the element?
They control bonding and chemical reactions.
Two atoms bond. One loses electrons and one gains electrons.What type of bond is this?
Ionic bond , because electrons are transferred , not shared.
If an atom loses all its electrons, is it still the same element?Why?
Yes, because the number of protons stays the same.
Why do atoms form bonds?
To achieve full outer shell.
Why are metals mostly found on the left side of the periodic table?
Metals usually have few valence electrons, so they tend to lose electrons easily and form positive ions.
Why does atomic size increases as you go down a group?
More energy levels(shells) are added.
If scientists change the number of neutrons in uranium, what changes and what stays the same?
Mass changes, but the element stays uranium.