Atomic theory/bonding/periodictrends-chapter 3 - chemistry of the environment

atomic theory

* developed by john dalton
* asserts that all matter is made up of nearly indestructible particles known as atoms
* atoms of a given element are similar in all \n respects
* atoms of one element are different from the atoms of all other elements
* Chemical compounds are formed when the atoms of two or more elements come together to form molecules

nucleus

* very dense center of an atom, containing most of the atom's mass
* protons and neutrons

atomic number

number of protons

electron

very light, negatively charge particles found in the space surrounding the nucleus

atomic mass

the sum of the protons and neutrons in an atom

isotopes

* same # of protons; different # of neutrons
* same atomic number; different atomic mass

atomic weight

weighted average of the isotopes of an element

periodic law

based on the idea that when elements are arranged in the order of their atomic numbers many properties will recur on a periodic basis

groups/families

* Vertical columns in the periodic table.
* Groups contain elements with similar chemical properties

periods/rows

horizontal rows on the periodic table

valence electrons

outer shell of electrons involved in chemical reactions

octet rule

theory that atoms react in such a way as to gain eight valence electrons

ion

chemical species containing a net charge

ionic bonding

* bonding between oppositely charged ions that is created by the **transfer of electrons**
* Simplest type of bonding

covalent bonding

bonding arrangement where valence electrons are **shared**