Chapter 2: Atoms and Elements Flashcards
Dalton’s Atomic Theory of Matter (4)
1) All matter is made of atoms
2) All atoms of a given element are identical in mass and chemical properties (atoms of different elements have different masses and chemical properties)
3) Definite proportions and multiple proportions
4) A chemical reaction involves combination, separation, and/or rearrangement of the atoms. Law of Conservation of Mass
Which postulet of Dalton’s Atomic Theory do we now know is false?
postulate 2; atoms can exist as isotopes
what did J.J. Thomson discover and how?
Thomson discovered the electron and concluded that all substances contain electrons. He also found charge to mass ratio of the electron using the cathode ray.
What did Robert Millikan discover and how?
Milikan determined the charge of an electron and found its mass. He used the oil-drop experiment.
What did Ernest Rutherford discover and how?
Using gold foil, Rutherford discovered alpha and beta particles. He developed the nuclear model of the atom
The nuclear model of the atom postulates (4):
1) atom is mostly empty space
2) positive charge and most of the mass is concentrated in the tiny nucleus
3) nucleus surrounded by electron cloud
4) electron cloud takes up most space in an atom
Protons, neutrons, electrons are what kind of particle
subatomic
what is atomic number (z)
number of protons in nucleus
what is mass number (a)
total number of protons and neutrons in the nucleus
how do you write an atomic symbol
A/Z X
what is an isotope
same element with different mass due to number of neutrons
what are horizontal rows on the periodic table called
periods
what are the 7 elements that exist as diatomic molecules
N2, H2, F2, O2, I2, Cl2, Br2
characteristics of alkali metals (4)
1) extremely reactive
2) soft
3) react vigorously with water
4) not found in elemental form in nature
characteristics of alkali earth metals (3)
1) very reactive
2) react vigorously with water
3) not found in elemental form in nature
