chem 60 latif exam 2
whats the law of conservation of mass?
"In a chemical reaction, mass is neither created nor destroyed."
What did Ernst Rutherford discover?
He found that the atom consists mostly of empty space, with its mass concentrated in a central positively charged nucleus.
what are the non metals on the periodic table
Hydrogen and anything above B Si Ge As Sb Te At
who discovered the electron?
JJ Thomson
who came up with the law of definite proportions?
Joseph Proust
what did leucippus and democritus propose?
Leucippus and Democritus proposed matter was composed of small indivisible particles
what did the nuclear theory of the atom propose?
Most of the atom's mass and all of it's positive charge are contained in a small core called the nucleus Most of the volume of the atom is empty space through which tiny, negatively charged electrons are dispersed There are as many electrons outside the nucleus as there positively charged particles (protons) inside the nucleus, so that the atom's overall charge is neutral
What model did J.J. Thompson propose?
Plum pudding model
What did Ernest Rutherford do?
Shot ALPHA PARTICLES at a gold plate to prove that there is a nucleus.
what is the periodic law
When the elements are arranged in order of increasing relative mass, certain sets of properties reoccur periodically.
What are halogens?
all elements in group 7
what are the metals of the periodic table
anything below H(hydrogen) and below B Si Ge As Sb Te At
how do i know an elements number of protons from looking at the periodic table ? how many protons does cs have
by looking at z the atomic number at the top of them chemical symbol. 55 protons
describe metaloids
display properties of both metals and nonmetals modertae condoctors of heat
true or false Atoms of the same element can have different numbers of neutrons
true
true or false cations and anions always occur together?
true
How reactive are noble gases?
unreactive
how reactive are alkali metals
very reactive
how reactive are the halogens
very reactive
whats the atomic mass unit(amu) of an electron? and the charge?
.00055 and -1
whats the atomic mass unit(amu) of a proton? and the charge?
1.0073 and 1+
whats the atomic mass unit(amu) of a neutron ? and the charge?
1.0087 and 0
in 1869 how many elements were discovered?
65 elements
if there are 18.0 g of water what is the oxygen to mass ratio?
8.0 to 1 so 8g of oxygen per 1 gram of hydrogen mass ration is mass of oxygen divided by mass of hydrogen
what are anions
Anions gain electrons and become negatively charged.
what are isotopes
Atoms of same element with differing number of neutrons
what do cations do
Cations lose an electron and become positively charged.
whats the law of definite proportions?
Compounds of the same type will always have the same mass ratio of elements
who created the periodic table
Dmitri Mendeleev
who disproved the plum pudding model
Ernest Rutherford
describe metals
Good conductors of electricity Good conductors of heat Ductile and malleable Shiny
what are the alkaline earth metals
Group 2 elements
what did john daltons atomic theory state?
each element is composed of tiny indestructible particles called atoms all atoms of an element have the same mass atoms combine in simple whole number ratios to form compounds
what are the alkali metals
every element except H in column 1
true or false Chemical compounds are not formed with defined ratios of elements
false
true or false as dalton sugests in his atomic theory all atoms of the same element have the same mass
false
what are nobel gasses
group 8 elements
In chemical reactions, atoms lose or gain electrons to form charged particles called?
ions
how do you determine ionic charge
number of protons minus number of electrons an element has
meaning of atomic mass
one twelfth of the mass of a carbon atom containg six protons and six neutrons
what does the nucleus contain?
protons and neutrons
how reactive are alkaline earth metals
reactive but not as much as alkali metals
describe nonmetals
some are solids and some are gasses at room temp -brittle (not malleable or ductile) -poor conductors of heat and electricity
what was the plum pudding model
the atom is a ball of positive charge with negative electrons embedded in it
what did rutherford develope
the nuclear theory of the atom
at the end of the 19th century what was the model of atoms?
the solid sphere model
what are elements defined by?
their number of protons
what did jj thompson discover about the electron
they were negatively charged smaller and lighter than atoms atoms must contain positive and negative charge
why did john dalton formulate the atomic theory
to explain the law of conservation of mass and law of definite proportions
