Chapter 2 Atoms, Elements, and Compounds Flashcards
define matter
anything that has mass or occupies space
what are the two classifications of matter
pure substances
mixtures
define chemistry
the study of matter, the structure and behavior
what are the things that define the property of matter
descriptions, observations, or measurements of matter
what are two types of properties
extensive
intensive
explain what it means to be an intensive property of matter
provide example
think salt
observations, measurements, or descriptions that do not depend on the quantity of the substance
example: salt is white. the fact that salt is white does not depend on the quantity of the salt
explain what it means to be an extensive property of matter
provide example
observations, descriptions, or measurements dependent on the quantity of the substance
example: mass and volume. if the salt weighs 3.5g, the property is dependent on the quantity
often, is the quantity resulting from the ratio of two extensive properties intensive or extensive
intensive
what is a mixture
two or more substances mixed together and can have different proportions of its ingredients
what is a chemical substance
provide example
matter that has only one possible composition, always has the same percentages of its components
example: table salt
what is a heterogeneous mixture
two or more components can be seen.
examples: oil and water, salt and pepper
what is a homogeneous mixture
provide example
when a mixture looks like a single substance
example: salt water
in a mixture, do individual substances keep their own identity?
yes
in a mixture, do any chemical processes or modifications occur?
no
from a mixture, can you recover any of the starting material in tact?
yes
explain what a pure substance is
something that has a fixed, constant composition
what are the two classifications of pure substances
elements
compounds
define a compound
substance that is made of two or more other substances
have a fixed composition
usually look different from their components
difficult to separate into their individual components
define elements
a pure substance that cannot be changed or broken down into anything else
define atom
the smallest part of an element that cannot be broken down any further
what does the atomic mass unit (amu) of an atom describe
describes the mass of an atom
what is the expression in scientific notation of how many amus equal grams
6.022 x 10^23 amu
what is a subatomic particle
a particle that atoms are made of
what are the 3 subatomic particles of an atom
proton
neutron
electron
what are the two important properties of a subatomic particle
electrical charge
mass
what two subatomic particles do all atoms contain
protons
electrons
which two subatomic particles have an opposite charge and are attracted to each other
protons
electrons
which subatomic particle has no electrical charge
neutrons
what does the nucleus of an atom contain
is it positively or negatively charged
a compact ball of the protons and neutrons
positively charged
what subatomic particle surrounds the nucleus
electrons
can one identify the path of an electron around the nucleus
no
define the atomic number, what does it represent
the number of protons in an atom
do all atoms of an element have the same number of protons
yes
do atoms normally have an electrical charge
what does the answer mean for the number of protons and electrons in an atom
no
they are usually the same amount to create a neutral charge
what is an electrically neutral atom
think # of protons and electrons
an atom with equal number of protons and electrons
how is the mass number of an atom calculated
adding the mass of protons and neutrons
how many amus do protons and neutrons weigh, approximately
1 amu
how do you express mass of an element
show examples of flourine with a mass number 10
10^F
F-10
flourine-10
what are shells of an atom
shells are layers surrounding the atom that contain electrons
how many electrons each the first four layers of the shell hold
2
8
18
32
which shell layer do electrons perfer to be in and why
inner most shell because they are attracted to the protons in the nucleus
what do the electrons in the outermost shell tell us about compounds
the ability for the element to form compounds and the formulas for those compounds are found by the number of electrons in the outer shell
what are the electrons in the outermost shell of the atom called
valence electrons
what is the outermost shell called in an atom
valence shell
do elements that have a similar number of valence electrons have similar behavior?
yes
what are the three classes of elements in the periodic table
metals
nonmetals
metalloids
are metals solid at room temperature
is there an exception
yes, except mercury, it’s a liquid
do metals conduct electricity well
yes
describe the appearance of metals
two metals look different, which ones
shiny when polished
silver or gray except copper and gold
can metals be bent and shaped
yes
are metalloids solid at room temperature
yes
describe the appearance of metalloids
gray and shiny when polished
do metalloids conduct electricity well
no
what happens to metalloids when they are bent
they break
are nonmetals a solid, gas, liquid or all three?
11 nonmetals are gases
5 solids
one (bromine) is liquid
describe the appearance of nonmetals
can be a multitude of colors
are not shiny
do nonmetals conduct electricty?
list two exceptions
no
except graphite the graphite form of carbon
do solid nonmetals bend or break
break
how are elements listed in the periodic table?
in order of atomic number
what are the rows on the periodic table called
periods
what is the vertical column called on the periodic table?
group
where are the representative elements on the periodic table and what are their columns labeled
far left and far right
A columns
where are the transition elements on the periodic table and how their columns (groups) labeled
in the middle between the representative elements
labeled B
what type of elements are on the left side of the periodic table
metals
what elements are on the right side of the periodic table
nonmetals
what elements are in the middle of the periodic table
metalloids
what are the elements in groups 1A
name one exception
Alkali Metals
H is not a metal
what are the elements in group 2A called
Alkaline Earth Metals
what are the elements in Group 7A called
halogens
what are the elements in Gropu 8A called
noble gases
which group on the periodic table are very reactive and combine with many other elements to form compounds
7A
which group on the periodic table rarely combines with any other elements
Group 8A
for the representative groups in the periodic table of elements, what does the group number represent?
the number of valence electrons in the elements in that group
each element has the same number of valence electrons
what does the period number represent on the periodic table of elements
the number of shells an element has
what are atoms that are the same element with different masses called?
isotopes
what happens to the mass of two atoms when they have a different number of neutrons
they have a different mass
what is the average mass of an atom of an element based on the distribution of isotopes we see on earth
atomic mass
how do you define mol
the atomic weight of an element expressed in grams
what is a formula unit
a group of atoms
what is a chemical formula
the written expression of a formula unit
what is a formula weight
total mass of all atoms in one formula unit
