chem chapter 3 test Flashcards
first to organize elements into a table was \_\_\_\_ how were (are) they organized
Dmitrie Mendeleev
increasing atomic mass
Chemists have always used the _____ of the elements to sort them out
properties
periods(rows) are _____ and there are ___ of them
groups(columns) are ____ and there are ____ of them
horizontal, 7
vertical, 18
what are the 4 organizational patterns to the modern day period table
increasing atomic number, metals nonmetals and metalloids, periods and groups, blocks (spdf)
what is the smallest particle of an element
atom
who was the first to suggest that atoms existed
who developed the scientific theory behind atoms
democritus, dalton
true or false
different atoms can never chemically combine in fixed ratios to form compounds
false
true or false
atoms can never change their identity during chemical reactions. They can rearrange to form different compounds
true
who conducted the gold fold experiment to discover protons
Rutherford
positive charge, 1 amu (atomic mass unit), within the nucleus
proton
no charge, 1 amu, within the nucleus
neutron
negative charge, 1/1840th of a proton or neutron, outside the nucleus
electron
who used the cathode ray tube to discover electrons’ charge
JJ Thomson
The _______ is the densest part of the atom, _____ charged, and contains most of the ___ of the atom
nucleus, positively, mass
atoms of the same element that have a different mass number
isotope
mass number= ___+____
protons+, neutrons0
an isotope has __________ atomic mass
whole number
the energy of an electron is determined by _____-distance from the nucleus
energy levels
what is a quantum
fixed amount of energy (each electron is described by 4 quantum numbers)
80% as a decimal is ___ with ____ sig figs
.8, 1
molar mass is measured in___
molecular mass is measure in ____
grams, amus
how would you find the molar mass of H2SO4
2(1.0)+32.1+64.0=98.1g
find the elements’ masses and add up
how do you find percent abundance of an element in a compound
put the molar mass of the element over the total molar mass of the compound. divide and multiply by 100
how many protons are in 12C
electrons?, neutrons?
6,6,6
the number of ____ in an element will never change
protons
all carbon atoms have __ protons
6
what do all hydrogen atoms (and ions) have in common
1 electron
what is the significance of the atomic number Z above each element in the periodic table
it’s the number of protons in the nucleus of that element
what feature distinguishes a neutral atoms from an ion
an ion is charged and has an unequal amount of protons and electrons. Atoms are neutral and have an equal amount of protons and neutrons
why is most of the mass of an atom within the nucleus
it has protons and neutrons while the outside only has electrons and free space
in large atoms the number of protons is ____ than the number of neutrons
less
uranium has 92 protons and 145 neutrons. write its symbol
237
U
92
A
X
Z
what does each represent
a-mass number
x-nuclide
z-atomic number
all elements have _______ isotopes
at least one
% composition=
massX/total mass x 100%
what error margin is acceptable
when adding percent compositions, what values besides 100% are acceptable?
10% error
99.9%, 100.1%
the mass of a mole=formula mass expressed in ___
grams
there are 22.4 L/
mole
there are _______ particles per mol
what particles are acceptable here and what is this number called
6.022 x 10^23
atoms, molecules, formula units, Avogadro’s number
every mole of something equals its formula mass of___
grams
.8%==
.008
Isotopes have ________ mass numbers (or, number of neutrons) but the __________ atomic number (number of protons)
Different, same
What is Cu?
Copper-64
How would you figure out how many H Atoms are in C12H22O11
Find out how many molecules total this is and multiply by 22
127.5 What place is the 2 in? 1? 7? 5? (Make sure you remember this in your answer with sig figs
Tens, hundreds, ones, tenths
The __________ of an element is the weighted average of the masses of the isotopes of that element
average atomic mass
