Atoms Flashcards
Daltons atomic theory (4)
1) everything is made of atoms
2) atoms of the same element are identical, vice versa
3) atoms of diff elements combine in whole # ratios to make compounds
4) chemical reactions involve the rearrangements of atoms. no new atoms are created/destroyed
subatomic particles
proton, electron, neutron
charge of proton
+
charge of electron
-
charge of neutron
0
proton relative mass
1
electron relative mass
0
neutron relative mass
1
what is the atomic #
number of protons
what is the mass number
how many protons + neutrons
how many electrons are in an atom
same as # of protons
what is the charge of an atom?
0/neutral
what is an isotope
atoms with a diff number of neutrons and same number of protons
amu formula
avg = mass1(percentage1) +…
who is mendeleev
russian chemist who created the first periodic table
who is henry mosley
chemis who arranged periodic table to what we use today (increased atomic #)
why is the periodic table called the periodic table
because of the periodic repetition
what is a group/family
verticale rows of the periodic table
have similar reactions
what is a period
a horizontal row in the periodic table
what are metal
- largest region
- conduct heat/electricity
- lustrous
-malleable
-ductile
what are metalloids
- have properties of metals and nonmetals
what are noble gases
group 8 elements
-exist in gaseous state at normal temp and are non reactive with other metals
what are alkali metals
group 1 elements
-highly reactive
what are alkaline metals
group 2 elements
smallest particle of an element?
atom
what particles form the nucleus?
protons & neutrons
how does the mass of a neutron compare to mass of a proton
basically the same, proton slightly heavier
atoms of the same elements arent always identical because…
of isotopes
what is the charge of the nucleus
positive
how to write nuclear symbols
mass #
Element
atomic #
what are halogens
non metals in period 17
what are sig figs
include all of the digits that are known plus one more that is estimated
rules for counting sig figs (4)
1) numbers other than 0 always count (ex. 3645 has 4 sig figs)
2) leading zeros do NOT count (ex. 0.0845 has 3 sig figs)
3) captive zeroes are always sig figs (ex. 16.07 has 4 sig figs)
4) trailing zeros are only sig figs if there’s a decimal point (ex. 2500.000 has 7 sig figs)
special situations where there’s an unlimited amount of sig figs (2)
1) counted items (ex. 12 people or 425 thumbtacks)
2) exactly defined quantities
how to convert grams
x1000 x1000
kg ———> grams———-> mg
<——— <———-
/1000 /1000
how to convert meters
milli-meter = 1000mm for 1m
centi-meter= 100 cm for 1m
density formula
d=m/v
is density a physical or chemical property?
physical
as density decreases, temperature…
increases
what is matter
matter is anything that
1) has mass
2) has volume (takes up space)
what are chemical properties
a property that can k my be observed by changing the composition of the material
(ex. flammability, decomposition, fermentation)
what are physical properties
a property that can be observed and measured without changing the materials composition
(ex. color, hardness, melting & boiling points)
if you can reverse it, it’s a physical change
who created the current periodic table
henry mosely
who created the first periodic table
mendeleev
what is an ion
a charged particle
two types of ions
1) cation
2) anion
what is a cation
ion with + charge
what is an anion
ion with - charge
what is electron configuration
ways elections are arranged in orbitals
what are the rules of electron configuration (3)
1) aufbau principle: electrons enter the lowest energy level first
2) pauli principle: only 2 electrons per orbital
3) hunds rule: when electrons occupy orbital of equal energy
what are unpaired electrons
an orbital with only one electron instead of 2
what are valence electrons
the highest principle energy level
what is the periodic trend for atomic size
increases as it goes ⬇️
increases as it goes ⬅️
what ionization energy
ionization energy is the amount of energy it takes to completely remove and election from a gaseous atom
what are the periodic trends for ionization
increases ⬆️
increases ➡️
periodic trend of melting/boiling point
highest in the middle
what is electronegativity
tendency for an atom to attract electrons to itself when combined with another atom
what are the periodic trends for electronegativitiy’s size
increases ⬆️
increases ➡️
what is empiricle formula
lowest whole number ratio of atoms in a compound
what is molecular formula
the true number of atoms of each element
how do you do molar conversions
mols x molar mass= mass
mols x 22.4 = volume
mols x 6.02 x 10^23= molecules
what are ionic compounds
metal + another metal
what are covalent compounds
metal + nonmetal
