Chapter 4 Flashcards
Matter
Anything with mass and volume.
Made of small particles.
Atom
The basic unit of matter.
What did Democritus believe?
Atoms are indivisible.
What are the 4 parts to Dalton’s atomic theory?
- Atoms are the basic unit of matter.
- Atoms of the same element are identical, atoms of different elements are different.
- Atoms of different elements can physically and chemically combine.
- Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms are never changed into other elements atoms as a result of chemical reactions
Mixture
A physical blend of atoms.
Compound
Chemically combining of particles.
How can we observe atoms?
Using a scanning tunneling microscope.
Is Dalton’s theory excepted?
Yes, except we know atoms are divisible.
Electrons
Negative charge and outside the nucleus.
Proton
Positive charge and inside the nucleus.
Neutron
No charge, inside the nucleus.
What did J.J. Thomas notice with magnets?
Opposites attract and the same repel.
What did J.J. Thomas first call atoms?
Corpuscles
What is the mass of an electron compared to a hydrogen atom?
1/1840 mass of a hydrogen atom.
Quarks
Smaller particles that make up subatomic particles.
Describe the “Plum Pudding” Model
In this model, the protons and neutrons were spread out in the atom.
Atomic Nucleus
Contains protons and nuetrons.
Overall positive charge.
Explain what happened to the alpha particles in Rutherford’s experiment?
- Most passed straight through with slight deflections.
- Some deflected at very large angles.
- Very few bounced back.
What is the atom mostly?
Empty space.
Nuclear Atom
Protons and neutrons are in the nucleus.
Electrons are distributed around the nucleus and occupy most of the atom’s volume.
Why are elements different?
They contain a different number of protons and neutrons.
Atomic Number
The number of protons in the nucleus of an atom.
Are protons and electrons equal?
Yes, in an electrically equal atom.
Mass Number
Mass number= protons + nuetrons
How else can the composition of an atom be represented?
Shorthand notation
Shorthand Notation Formula
mass number (over) atomic number
Isotopes
Atoms that have the same number of protons but a different number of neutrons.
This gives them a different mass number, but the same chemical behavior.
Hydrogen-1
proton-1
electron-1
nuetron-0
Hydrogen-2
proton-1
electron-1
nuetron-1
Hydrogen-3
proton-1
electron-1
nuetron-2
What is the atomic weight of an element?
A weighted average mass of an atom.
How do you calculate the atomic weight of an element?
Multiply the mass of each isotope by its natural abundance, expressed in decimal, and then add the products.
Periodic Table
An arrangement of elements in which elements are separated into groups based on a set of repeating patterns.
How is the periodic table arranged?
In order of increasing atomic number.
Periods- 7 horizontal rows
Groups- verticle columns
Elements have similar chemical or physical properties.
