physics chapter 2 test Flashcards
What was Democritus Theory?
◾️First earliest theory
◾️All things were made of tiny, indivisible structures called atoms
◾️Atoms were indestructible and different in size and shape
◾️theorized that the nature of the object depended on its atoms (sweet=smooth atoms, bitter= sharp atoms)
The word atom comes from?
The Greek word “atomos” meaning indivisible.
What was John Dalton’s theory?
◾️elements combined to form compounds
◾️all elements compose of tiny indivisible and indestructible particles
◾️atoms were unique to each element in size and mass
◾️chemical reaction was a rearrangement of atoms
◾️chemist who developed the theory that elements combined in definite proportions to form compounds
Dmitri Mendeleev’s work
Organized known elements into the periodic table in order of increasing atomic mass and having similar properties
What was Joseph John Thomson’s discovery?
Electrons
What was Niels Bohr’s work?
Refined Rutherford’s work bringing us to the theory and model of the atom we are familiar with
What is the modern atomic theory?
The atom is the building block of matter. Bohr’s theory describes an atom as having three fundamental properties
Each atom has a nucleus… What is the nucleus made of?
Protons and neutrons
Describe a proton
Positively charged and has a mass of 1.673x10^-27 kg
Describe the neutron
No electrical charge and a mass of 1.675x10^-27
What’s the difference between the proton and neutron?
Proton has a positive charge and a neutron has no electrical charge. Also slight mass difference
Describe the electron
Negative electrical charge and a mass of 9.109x10^-31
Know the technical aspect behind a neutral atom?
Equal number of protons and neutrons. It has no electrical charge since the positive and negative will cancel eachother out.
What happens if the balance of an atom is disrupted?
Charge becomes positive if there are more protons or negative if there are more electrons. The atom will either gain or lose an electron
What is a negative ion?
The gaining of an extra electron making a negative electrical charge
What is a positive ion
Atom losing an electron. The positive charge will out number the negative charge creating a net positive charge
What is binding energy
A force of attraction that holds the nucleus of an atom together and holds electrons in orbit around the nucleus
What is binding energy a measure of?
The amount of energy necessary to split an Atom
What are electron shells
Defined energy level at a distance from the nucleus within which electrons orbit. This describes a sphere around the nucleus
How are the electron shells labeled
K(nearest nucleus) moving outward with L M N O P and so on
How does the electron shell fill?
K shell outward with outermost shells not necessarily filling completely
How many electrons can the 1st shell hold?
2
Which shell has the greatest binding energy?
K
What’s a valence shell?
Outermost shell of an atom
What’s an atomic number?
Number of protons it contains in its nucleus
What’s the atomic mass number
The number of protons and neutrons an atom has in its nucleus
What’s a molecule?
Formed when two or more atoms join together
◾️fixed ratios of each type of constituent atom resulting in the predictable mass
What’s a compound
Molecule that contains at least two different elements. Combination of elements in definite proportions
What are 2 primary ways atoms bond?
Ionic and covalent bond
What is ionic bonding based upon
The attraction of opposite charges
What is covalent bonding based on?
Two atoms sharing electrons that then orbit the nuclei
