Unit 1 - Matter, Chemical Trends, and Chemical Bonding

Chemistry

The science that deals with the composition, structure, properties, and transformation of substances.

Isotope

atoms of the same element with the same number of protons but different number of neutrons resulting in different atomic masses

Radioisotope

An isotope with an unstable nucleus that decays over time, emitting radiation.

Particle Theory of Matter

• Matter is made of particles

• Particles are in motion

• Particles attract each other

• Particles have spaces between them

• Particles move faster as temperature increases

Ions

Atoms that have gained or lost electrons.

Molecules

Two or more nonmetals bonded together by sharing electrons

Difference Between Atomic Models

• Dalton's Solid Sphere Model: Atoms are indivisible solid spheres.

• Thomson's Plum Pudding Model: Atoms consist of a positively charged 'pudding' with negatively charged 'plums' (electrons) embedded in it.

• Rutherford's Nuclear Model: Atoms have a small, dense, positively charged nucleus, with electrons orbiting around it.

• Bohr's Planetary Model: Electrons orbit the nucleus in fixed energy levels or shells.

• Quantum Mechanical Model: Electrons exist in probability clouds.

atomic mass

a weighted average between all isotopes of an element. mass = protons + neutrons

effective nuclear charge

the apparent nuclear charge, as experienced by the outermost electrons of an atom, as a result of the shielding by the inner shell electrons

electron affinity

The energy absorbed or released when an electron is added to a neutral atom in the gaseous state

electronegativity

the ability to pull an electron to and from other atoms NO UNIT.

ionization energy

the amount of energy required to remove the outermost electron from an atom or ion in the gaseous state

melting point

boiling point

ionic bond

force of electrostatic attraction between two ions

periodic law

When elements are arranged by atomic number, their chemical and physical properties recur periodically

electron affinity energy release meaning

the resulting negatively charged ion will be stable

electron affinity energy required meaning

the resulting negatively charged ion will be unstable and will soon lose the electron

in ionic compounds, metals tend to ___ electrons.

lose

in ionic compounds, nonmetals tend to _____ electrons.

gain

atom radii

How big an atom is

Atomic radii ____ as you move L → R across a period. Since ____ are in the same shell, the number of ______ increases as well as the _______ _______ force on each electron.

decreases, electrons, protons, attractive, nuclear

Atomic radii ____ as you move down a group. With each step down a group, the number of occupied ____ are filled. The outer _____ are not as ______ to the nucleus.

increases, shells, electrons, attracted

cation radii are usually _____ than their atoms because of the _____ of valence ________.

smaller, loss, electrons

anion radii are usually _____ than their atoms because there are more _____ than ______, there is less ______ _______ per electron, and more _____ between electrons

larger, electrons, protons, nuclear attraction, repulsion

First Ionization Energy ______ as you move from L → R across a period; The atomic radius _____ across the period, so the electrons are ____ to the _____ which means there’s a _____ force of attraction. The number of _____ also increase. _______ attraction is stronger, requiring more ______ to remove an electron.

increases, decreases, closer, nucleus, stronger, protons, nuclear, energy

First Ionization Energy _____ as you move down a group.

The atomic radius _______, so the electrons are further away from the attractive force of the __________.

There is also an increasing number of __________ (orbits):

More electron __________ results in less force of attraction from the nucleus.

So, less __________ is required to remove an electron from the atom.

decreases, increases, nucleus, shells, shielding, energy

Electron Affinity _____ as you move from L → R across a period. Electron Affinity ______ as you move down a group.

When added to an atom, an __________ is attracted to the __________ of the atom, while being repelled by the existing __________:

If the __________ is greater than the repulsion, the electron affinity will be __________.

If the __________ is greater than the attraction, the electron affinity will be __________.

increases, decreases, electron, nucleus, electrons, attraction, high, repulsion, low

Electronegativity _____ as you move from L→R across a period. Electronegativity ______ as you move down a group. Why?

Because the positively charged __________ of a small atom can get much closer to the __________ of another atom, this nucleus can exert a stronger __________ force on those electrons.

increases, decreases, nucleus, electrons, attractive

covalent bond

force of attraction resulting from the sharing electrons