CH 18 Chemistry Of Earth and The Known Universe

Atomic StructureAtomic StructureSubatomic ParticlesSubatomic Particles

ProtonProton- P- P+ + positive charged - in nucleuspositive charged - in nucleus Number of P+ distinguishes one atom from anotherNumber of P+ distinguishes one atom from another Made of 2 up quarks (+2/3 charge) and 1 down Made of 2 up quarks (+2/3 charge) and 1 down

quark (-1/3 charge) quark (-1/3 charge)

NeutronNeutron- N- No o neutral charged - in nucleusneutral charged - in nucleus Made of 2 down quarks and 1 up quarkMade of 2 down quarks and 1 up quark

ElectronsElectrons ElectronElectron- e- e--

negatively charged negatively charged - swarming in - swarming in energy levels energy levels around nucleus of around nucleus of atom (electron atom (electron cloud).cloud).

Electrons (e-) are attracted to the positively charged protons (P+) in the nucleus, helping them remain close to the nucleus in swarming levels.

Energy LevelsEnergy LevelsElectrons e- have a specific amount of Electrons e- have a specific amount of

energy when in each level.energy when in each level.K – Shell has least energyK – Shell has least energyM – Shell has most energy (as far as M – Shell has most energy (as far as

we’re going)we’re going)e- can occupy only 1 level at a timee- can occupy only 1 level at a timeNo matter how many levels the outer No matter how many levels the outer

level (valence) can have no more than level (valence) can have no more than 8 e- 8 e-

Most stable atoms have 8 e- in valenceMost stable atoms have 8 e- in valence

18.2 Comparing Atoms18.2 Comparing Atoms The number of P+ determines the type of atom. The number of P+ determines the type of atom. If you change the number of P+ you change the If you change the number of P+ you change the

atom.atom.

18.2 Atomic Number18.2 Atomic Number The Atomic Number is total number of The Atomic Number is total number of

protons in the nucleus of an atom.protons in the nucleus of an atom.

18.2 Mass Number• The total number of

protons and neutrons in the nucleus of an atom is called the Mass Number or Atomic Mass.

18.2 Isotopes18.2 Isotopes Isotopes are atoms of the same Isotopes are atoms of the same

element that have different element that have different numbers of neutrons.numbers of neutrons.

Each of the below atoms are Each of the below atoms are hydrogen, but they are all hydrogen, but they are all isotopes of hydrogen. isotopes of hydrogen.

IsotopesIsotopes

• An atom can have 2 or more isotopes

• Isotopes have different numbers of neutrons– Thus different mass numbers– More N add mass to atom– Heavier elements are radioactive (give off N)

18.3 The Periodic Table of 18.3 The Periodic Table of ElementsElements

Elements Elements are made up of only are made up of only one kind of atom.one kind of atom.

CompoundsCompounds are made up of are made up of combinations of atoms.combinations of atoms.

Elements that are part of the Elements that are part of the same same groupgroup act alike. act alike.

18.3 The Periodic Table 18.3 The Periodic Table of Elementsof Elements

Dimitri MendeleevDimitri Mendeleev (1834- (1834- 1907) organized information 1907) organized information about all the known about all the known elements in a table that elements in a table that visually organized the visually organized the similarities between them.similarities between them.

Mendeleev placed each Mendeleev placed each element on the table in a element on the table in a certain row and column certain row and column based on its based on its propertiesproperties..

The chemical symbol is an abbreviation of The chemical symbol is an abbreviation of the element’s scientific name.the element’s scientific name.