Scientific Method
Observations- collected during experiments Law- concise statement of an observed pattern/behavior Hypothesis- an attempt to explain an observation that can be tested with experimentation Theory or Model- is a set of tested hypotheses that have been confirmed by multiple experiments. It explains past behavior and predicts future behavior
Protons
are positively charged particles found in the nucleus
Neutrons
are electronically neutral particles found in the nucleus Neutrons are slightly larger than protons
Electrons
are negatively charged particles distributed around the nucleus
Atoms
_____ are neutral if they have the same number of charged protons and electrons, balancing positive and negative charges. As long as the number of electron and protons are the same, the charges will balance
Compound
If both letters are capitalized it is an compound
Groups
are the vertical columns in the periodic table
Periods
are horizontal row of elements
The heavy zigzag line
Separates metals from non-metals on the periodic table. Metalloids border the zigzag line
Atomic Symbols, Number and Mass
Atomic number, Z = the number of protons in nucleus
Mass number (whole number), A = the sum of protons and neutrons
The number of neutrons = mass number − atomic number
The number of electrons = number of protons (for a neutral atom)
Ion charge = #p − #e-
Ionic Bonds
One atoms gains, one loses electrons(s), but both become attracted to each other (and happy) as a result
Isotopes
Isotopes are atoms of an element with the same number of protons, but a different number of neutrons. Isotopes also have the same atomic number, but a different mass number. Only difference is neutrons so the mass changes
Avg atomic mass
(fractional abundance of isotope 1 times its atomic mass) + (fractional abundance of isotype 2 times its atomic mass)
Wavelength(λ)
is the distance between identical points on successive waves The shortest wavelengths are gamma rays, and the longest are radio waves
Frequency(ν)
is the number of waves that pass through a particular point in one second As wavelength increase, frequency decreases ↑λ →ν ↓ and vice versa
Electromagnetic (EM) radiation
is a form of energy that is all around us and takes many forms.
Wavelength-frequency-Energy relationship
Long wavelength(λ) → small frequency(ν) → low energy Short wavelength(λ) → high frequency(ν) → high energy
line spectra
a series of colored lines with dark spaces in between
Bohr Atom
Each orbit was at a specific energy level, which was designated by a quantum number, n Electrons jump between levels by absorbing or emitting photons of particular wavelengths Only works for hydrogen
energy level diagram
The lowest possible energy state is said to be in the ground state, in which n= 1 Excited state, higher energy levels, where n is any integer greater than 1 (2, 3, 4, 5...).
Orbitals
Three dimensional regions in space where electrons are likely to be found; not a circular pathway
Atomic Orbitals
These sublevels (referred to as subshells: s, p, d, and f) contain spaces for the electron that we call orbitals The number of energy sublevels and the number of orbitals depend on the value of the principalquantum number (n),
s orbitals
letter s means a spherical orbital Electron density decreases as we move away from the nucleus
p orbitals
The letter p means a two-lobed orbital A p sublevel contains three p orbitals that are shaped like dumbbells
d and f orbitals
Beginning with the third principal energy level (n = 3), there is also a d sublevel containing five d orbitals Four of the d orbitals (dxy, dxz, dyz, and dx2 - y2) have clover-leaf shape (four lobes) either in the plane or on the axes of the xyz probability plot
Order of the electron orbital energy levels
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p
Pauli exclusion principle (first rule)
only two electrons in an atom can occupy an orbital and those two electrons must have opposite spins.
Aufbau principle states (second rule)
that electrons are added to the lowest energy orbitals first before moving to higher energy orbitals.
Hund's rule (third rule)
the most stable arrangement of electrons is the one in which the number of electrons with the same spin is maximized. Every orbital in a sublevel is singly occupied before any orbital is doubly occupied
Abbreviation Electron Configurations
The electron configuration of all elements except hydrogen and helium can be represented using noble gas core
Valence Electrons
The outermost electrons in an atom, those with highest principal quantum number.
Core Electrons
Electrons in completed shells.
Lewis Dot Symbols
Each dot represents a valence electron The maximum number of dots around an element's symbol is eight We don't put a second dot in any position (left, right, top, or bottom) until there are single dots in all the positions
Atomic Size
Depicts the relative atomic sizes of main group elements In general, as we go across a period from right to left,the atomic radius increases In general, atomic radius increases in going down a group From left to right, as atomic number and mass increase, atomic size decreases.
Ionization energy (IE)
is the minimum energy to remove an electron from an atom
Electron affinity (EA)
is the ability of an atom to gain an electron.
Cation
An ion with a positive charge (An atom the loses one or more electrons becomes positively charged, and we refer to it as a cation) Cations are smaller than their neutral atoms because the electron-proton attraction increases
Anion
An ion with a negative charge (An at, that gains one or more electrons becomes negatively charged, and we refer to it as an anion Anions are smaller than their neutral atoms because the electron-proton attraction decreases
Isoelectronic
Describes two or more species with identical electron configurations
Substance
A _______ is a form of matter that has a specific, universally constant composition and distinct properties such as color, smell, and taste.
Solid
In a _____, particles are held close together in a orderly fashion with little freedom of motion
Liquid
Particles in a _____ are also closer together, but are not held rigidly in position; they can move around within the ______.
Gas
In a _____, the particles are separated by distances that are very large compared to the size of the particles.
Mixture
A _______ is a combination of two or more substances in which each substance retains its distinct identity
Homogeneous Mixture
__________ _________ A mixture in which the composition is uniform. Also called a solution.
Heterogeneous Mixture
________ ________ A mixture in which the composition varies
Quantitative
(measured and expressed with a number)
Physical property
A property that can be observed and measured without changing the identity of a substance.
Physical change
A process in which the state of matter changes but the identity of the matter does not change
Chemical properties
Any property of a substance that cannot be studied without converting the substance into some other substance
Chemical change
A process in which one or more substances are changed into one or more new substances.
Binary Ionic compounds
Ionic compound consisting of two elements
Type I compounds
Ionic compound in which cation has only one possible charge.
Type II compound
Ionic compounds in which the cation may have more than one charge.
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