Chemistry Chapter 4
How many electrons are in an atom that has an atomic number of 34, an atomic mass of 74 and a charge of -2?
36
An atom has 5 neutrons and a mass number of 9. How many protons does it have?
4
An atom has 10 protons and a mass number of 18. It has __ neutrons
8
Who FIRST thought of the atom (atomos)?
Democritus
J.J. Thomson provided evidence that an atom...
contains negatively charged particles
What do chemical reactions change?
electrons surrounding an atom
Ernest Rutherford discovered that atoms were mostly _________________.
empty space
How did Rutherford discover the proton
gold foil experiment
Where did Democritus live?
greece
What is an alpha particle equivalent to?
helium
atoms with the same number of protons but different numbers of neutrons
isotopes
Dalton's theory also conveniently explained what?
law of conservation of mass
In a correctly written symbol what would be located in the "A" position? A X Z
mass number
What are electrons?
negatively charged particles
What quantities vary between isotopes of an element?
neutrons and atomic mass
the central region of an atom where its neutrons and protons are is its...
nucleus
Atomic number is equal to...
number of protons and number of electrons
What is John Dalton's atomic theory based on?
numerous scientific experiments
What determined the size of the charge of the electron?
oil drop experiment
What was Millikan most famous for?
oil drop experiment
What kind of charge do protons have?
positive
Ernst Rutherford discovered which part of the atom through the use of gold foil?
proton
a subatomic particle in an atom's nucleus that has a positive charge of 1+
proton
The primary factor in determining an atom's stability is its ratio of neutrons to...
protons
Two isotopes of an unknown element have the same number of:
protons and electrons
What does the nucleus of an atom contain?
protons and neutrons
According to democritus atoms are...
solid, homogenous, and indivisible
What does the neutron-to-proton ratio of an atom's nucleus determine?
stability
Democritus thought that matter was made of tiny particles
that could not be divided
What did Aristotle not believe in?
the existence of atoms
The atomic mass of an element is a...
weighted average of the masses of all of its naturally occurring isotopes
What is the relative size of protons, neutrons, and electrons?
1 atomic mass unit
How many protons are in an atom with an atomic number of 20, an atomic mass of 45, and a charge of +2?
20
How many protons does this isotope of titanium have? 48 Ti 22
22
How many neutrons does the isotope of lithium have? 8 Li 3
5
an atom with atomic number 6 would have how many protons
6
Who was a specific ancient scholar that believed the earth was made of earth, water, air, and fire?
Aristotle
Who disagreed with Democritus and why?
Aristotle did not believe that empty space existed
Which of the following is NOT part of Dalton's atomic theory?
Atoms contain subatomic particles
Place the following scientists in order, from earliest to latest: A) Ernest Rutherford B) J.J. Thomson C) John Dalton
C, B, A
People have always agreed that matter is made of atoms.
False
What contribution did John Dalton make to atomic theory?
He discovered that every element consisted of one type of atom
What scientist is best known for his "Plum Pudding" model of the atom?
J.J. Tomson
Which scientists discovered a positively charged nucleus in an atom?
J.J. thomson
Who received the nobel prize in 1935 for discovering the existence of neutrons?
James chadwick
What scientist first developed 4 rules for atomic theory, and helped kick start modern chemistry?
John Dalton
Name 3 types of radiation
alpha (charge of 2+), beta (1-), and gamma (no charge)
How is modern periodic table arranged?
arranged by ascending order of protons
The number of protons and neutrons combined is called...
atomic mass
mass number is equal to...
atomic number + number of neutrons
What do these isotopes of carbon all have in common? 12 13 14 C C C 12.00000 13.0035 14.0
atomic number and electrons
All matter is made of what?
atoms
How do scientists know how atoms are structured?
by running experiments that expose their properties
Who stated that all atoms of the same element are exactly alike?
dalton
Who was the first person to propose the existence of atoms?
democritus
What did many ancient scholars believe the earth was made of?
earth, water, air, and fire
Which particle did scientists discover with the cathode ray tube?
electron
Which subatomic particle is found outside of the nucleus?
electron
According to Dalton's observation, when elements combine in a compound,
the ratio of their masses is always the same
Rutherford's gold foil experiment provided evidence that...
there is a dense positively charged nucleus at the center of an atom
John Dalton modeled the atom as a...
tiny solid sphere, with a known mass