EXAM 2 2-1 : 2-2 Flashcards
What are the three basic types of subatomic particles in an atom?
Protons
Neutrons
Electrons
How are protons, electrons, and neutrons different, in terms of their mass, charge, and location
within an atom?
protons = + charge (in the nucleus) / mass #1
neutrons = no charge (in the nucleus) / mass #1
electrons = - charge (“clouds” orbiting the nucleus) / mass # close to 0
What is meant by isotopes of an atom?
atoms with the same number of protons but different numbers of neutrons.
example: 1H, 2H, 3H are different isotopes of hydrogen.
What is meant by the half-life of a radioactive isotope?
the time it takes for exactly one-half of the atoms to breakdown
What does the octet rule tell us about the electrons of an atom?
Electrons like to stay close to the nucleus, but
there is only room in each shell for a certain
number of electrons
– The shell closest to the atom’s nucleus has room for
only 2 electrons
– The second and third shells can each hold up to 8
electrons : octet rule
How (and why) does an atom become a positive or negative ion?
The gain or loss of electrons/change in the electrical charge.
Loss of electrons: formation of positive ions/ more protons than electrons.
Gain of electrons: formation of negative ions/more electrons than protons.
What is an ionic bond?
positive attracts negative/positive ion will form temporary bond with a negative ion
What does pH measure?
ph is a measure of the concentration of H+ [H+] in a solution.
What is the pH of a neutral solution (distilled water)? How about an acid or a base?
ph = 7: a natural solution (such as pure water)
ph = (less than) 7: an acidic solution (acid)
ph = (greater than 7: an basic solution (base)
What is a covalent bond?
covalent bonds - two atoms share one or more pairs of electrons.
single covalent bond - two atoms share one pair of electrons.
double covalent bond - two atoms share two pairs of electrons.
What is the difference between a non-polar covalent bond, and a polar covalent bond?
polar-covalent bonds: some pairs of atoms share electrons unequally
non-polar-covalent bonds: share electrons equally
Why do hydrogen bonds form, and why is a water molecule so good at doing this?
hydrogen atoms are always weak;
water molecules are good at this because of their polar structure, it can dissolve almost any substance that is either polar/ionic.
__________________ is everything that has mass (weight) and takes up space.
matter
Matter is made up of about 100 pure substances called ______________________________
elements
The smallest bit of any element is called an ________________________.
atom
Although an atom can’t be broken down into smaller units and still be the same substance, it is
made up of three smaller particles. ______________________ have a positive charge and are
found in the atom’s nucleus. ______________________ have no charge and are also found in
the atom’s nucleus. ___________________________ are found in “clouds” surrounding the
nucleus. They have a negative charge, and have almost no mass (compared to the first two
types of subatomic particles).
- protons
- neutrons
- electrons
The number of _________________ in an atom determines what type of element it is. Change
this number, and the atom becomes a different element.
protons
Different ______________________________ of an atom have the same number of protons,
but different numbers of neutrons. (Some of these are radioactive.
isotopes
The cloud or shell closest to an atom’s nucleus has room for only _______ electrons. The next
two shells farther out have room for ________ electrons. (This is called the octet rule.)
- 2
- 8
As a consequence of the octet rule, any particular atom is “stable” (it is unlikely to react with
other atoms) if _______________________________________________________.
its outer electron shell is full (has 8 electrons in it, except for the first shell, which can only hold 2 electrons).
An atom of sulfur (atomic number 16) has ________ electrons in its first shell, __________
electrons in its second shell, and _________ electrons in its third (outer) shell.
- 2
- 8
- 6
When an atom such as potassium loses the only electron in its outer shell, it becomes a
_________________________ (be specific).
potassium ion (K⁺)
When an atom such as fluorine gains one electron in order to fill its outer electron shell, it becomes a _________________________ (be specific).
fluoride ion (F⁻).
An __________________________ is a bond between a positive ion and a negative ion.
ionic bond
_______________ is a measure of the hydrogen ion concentration of a solution. If it is
__________________, the solution is an acid. If it is ________________________, the solution
is a base (or alkaline solution).
- pH
- low
- high
