chem test 2 Flashcards
atoms
building blocks of matter, smallest particle of an element
law of conservation of mass
mass is neither created nor destroyed during ordinary chemical reactions or physical changes
law of definite proportions
a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or the source of the compound
Law of multiple proportions
If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers
What were the 5 points of Dalton’s atomic theory?
- All matter is composed of extremely small particles called atoms
- Atoms of a given element are identical in size, mass and other properties
- Atoms cannot be subdivided, created or destroyed
- Atoms of different elements combine in simple whole-number ratios to form chemical compounds
- In chemical reactions, atoms are combined, separated, or rearranged
What are the revisions to Dalton’s atomic theory?
- Atoms are divisible into even smaller particles
- Atoms of a given element can have different masses
- Atoms can be destroyed
what’s the atomic nucleus
Atomic nucleus - the small, densely packed, positively charged central portion of the atom, that contains nearly all of its mass but nearly none of its volume. made up of protons and neutrons.
neutron
the neutral particle of the nucleus of an atom
proton
the positively charged particle of the nucleus of an atom
electron
the negatively charged particles of an atom, surrounds the nucleus.
What led to the discovery of electrons?
In the late 1800s, electric current was passed through cathode ray tubes. It was discovered that the cathode ray was attracted to the positive pole of a magnet and repelled by the negative pole
-This led to the discovery of electrons
atomic number
number of protons
mass number
protons + neutrons
how many are the electrons
the same as protons
