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37 Cards in this Set

  • Front
  • Back
-Anything that has mass and takes up space
-all matter is made up of various combinations of the simple forms of matter called the chemical elements. An element is a substance that consists only of one kind of atom
-each different pure kind of matter
-a single, pure for of matter, not a mixture of several different kinds of matter (not flesh softdrinks b/c they are complex mixtures)
the same throughout, even on a microscopic scale
identification of the substances mixturex contain
chemical elements
-basic building blocks of matter and in various combinations make up all the matter on Earth
-define elements on the basis of differences at teh atomic level
-smalles particle of an element
-comes from teh Greek word "not cuttable"
-1st argument made by JOHN DALTON
John Dalton
-first thought of the idea of atom in 1807
-oxygen adn magnesium experiement: found that the mass of oxygen is proportional to that of magnesium
substance composed of only one kind of atom
-the level that deals with the properties of large, visible objects
microscopic level
-level that can not be seen with the eye
sympolic language
ties macro and microscopic levels together by describing macroscopic changes in terms of atoms
chemical symbol
-the one or two letters tah represent individual elements
-found int he periodic table
What is the most abundant element in universe?
(in terms of the # of atoms)

What are the most abundant elements in the crust of the earth?
Oxygen and silicon
What are the most abundant elements in teh human body?
hydorgen, oxygen and carbon
Model of atoms
1. Atoms are mad eup of subatomic particles called electrons, protons, and neutrons
2. The protons and neutrons form a compact, ecntral body called the nucleus of the atom
3. The electrons are distributed in a space like cloud around the nucleus
subatomic particle
A particle smaller than an atom (ex: proton, neutron, electron)
-A negatively charged subatomic particle found outside the nucleus of an atom
-much less massive than a proton, nearly 2000 times lighter
-An electrically bneutral subatomic particle found in the nucleus of an atom
-it has the approximately the same mass as a proton, thereby not affecting teh charge (neutral) but add substantially to the mass of the atom
-known jointly with protons as NUCLEONS
A positively charged subatomic particle found in the nucleus of an atom
central body of an atom formed by a protons and neutrons
nuclear atom
model of an atom
JJ Thomson
-1897 earliest experimental evidence for the existence of an internal structure of atoms
-investigated "cathode rays"
found that the charged particles were the same regardless of teh metal he sed for the cathode and measured the ratio of thier charges to their mass
- therefore discovered electrons
cathode rays
rays that are emitted from a metal electrode (electrical contact) when a high potential difference (hight voltage) is applied between that electrode and another one in an evacuated glass tube
mass of electron
9.109 * 10 ^-28 g
What is the charge of atoms?
Overall zero atoms hvae zero charges, whcih is ehy each atomj must contain enough positive charge to cancel the negative charge
alpha particles
∝ streams of positively charged particles. These particles came from a sample of teh radioactive gas radon
Atomic nucleus
-pointlike positively charged region
-dense pointlike centers of positive charge surrounded by a large calume of mostly empty space
Where are electrons in atom?
Thinly distrubuted throughout the space around the nucleus.
atomic number
-the number of protons in an atomic nucleus
-first accurately determined by HG Moseley
-Ex: hydrogen has one proton so we know the atomic number is 1
-= to the number of electrons outside the nucleus
Nuclear Atom
-All + charge adn alsomst all teh mass in concentrated in a tiny nucleus
- the - charged electrons surround the nucleus like a cloud
-atomic number is teh number of protons in teh nucleus
-there is an equal number of electrons outside the nucleus
Mass spectrometer
-A device that can be used for determining the mass of a given type of atom
neutrons adn protons that are found in the nuclus (because they are very similar particles)
mass number
total number of protons and neutrons in a nucleus
-Atoms with the same atomic number (belonging to the same element) but different mass numbers
-have teh same number of protons but different numbers of neutrons
-named by writing its mass number after the name of the element (i.e. neon -20, neon-21)
-Its symbol is written by adding the mas number as a superscript to the left of the chemical symbol
Sometimes the atomic number is included as a subscript on teh lower left
-name comes from Greek work for "equal place"
Big Bang
According to current ideas, hydrogen and helium were formed in teh big Bang. The heavier elements were made inside stars adn then scattered throughout space