Chemistry Unit 1 Study guide

Matter

Anything that has mass and occupies space

Atoms

The smallest unit of an element that retains its chemical properties.

Element

A substance that consists of only one type of atom.

Chemical Symbol

Letter representation of an element

Molecule

A group of two or more atoms bonded together.

Compound

A substance formed when two or more different elements are chemically bonded together.

Water Vapor (Gas)

Held together by attractive forces.

They are far apart and move freely

Water (Liquid)

Held close together by attractive forces.

but the molecules can still move around

Ice (Solid)

In solid water or ice, the molecules are located in fixed patterns by attractive forces.

Still vibrates back and forth.

Energy

The capacity to move, do work, change matter, or produce that.

Kinetic Energy

the energy of an object’s motion

ex) the ball when someone kicked

Thermal Energy

The total kinetic energy of the atoms of a substance.

Potential Energy

the energy stored in a system

Chemical Potential

energy stored in the chemical bonds of a structure.

Subatomic

Smaller than an atom that include protons, neutrons, and electrons.

System

a part of the universe on which you focus your attention.

Surroundings

everything in the universe outside of the system

Macroscopic property

a characteristic of matter that is large enough to see, handle, or measure without magnification

Emission Spectra

the pattern is formed when light passes through a prism or distraction.

Energy levels

the specific energies of electron in an atom or other system can have.

Quantum

the amount of energy needed to move an electron from one energy level to another

The Bohr Model

Developed to explain the hydrogen emission spectrum (but couldn’t)

Proton

Positive charge, in the nucleus

Neutron

Neutral charge, in the nucleus

Electron

Negative Charge, orbits the nucleus

Nucleus

Center of an atom (Proton+Neutron)

Automic mass

number of protons plus neutrons

Isotopes

Same number of protons, but different number of neutrons.

Dalton Model

John Dalton, Billiard ball model: Proposed that atoms are solid, indivisible particles.

Thomson’s Model

J.J. Thomson: Discovered electrons, and proposed a plum pudding model, in which atoms were thought to be positive spheres with electrons scattered inside, like raisins in a pudding.

Rutherford’s Model

Ernest Rutherford: Gold foil experiment, and discovered the nucleus. He proposed that atoms have a small, dense nucleus at the center with electrons orbiting around it, leading to the “nuclear model.”

Bohr’s Model

Niels Bohr: Planetary model, Quantized energy levels or “shells”.

Quantum Mechanical Model

Erwin Schrodinger and others: Describes electrons as existing in probabilistic “clouds” or orbitals around the nucleus, rather than fixed orbits. It is the most accurate model used today.

Modern Atomic Model

Central nucleus consists of protons and neutrons, the electrons are orbiting outside the nucleus in the electron shells.

Electron Configuration

the arrangement of electrons in orbits around the atomic nucleus.

Ex) 12Mg → 1s² 2s² 2p^6 3s²

Condensed Electron Configuration

shorten ver of electron configuration

Ex) 12Mg → 1s² 2s² 2p^6 3s² → [Ne] 3s²

Valance Electron

Outmost S and P orbitals

Same group → Same number of Valance Electrons (similar chemical properties)

Ground State

the lowest allowed energy state of an atom, molecule, or ion.

Ex) 9F→ 1s² 2s² 2p^5

Excited State

energy state greater than its ground state (when a valence electron absorbs energy)

Ex) 9F^+ → 1s² 2s^1 2p^5 3s^1