Science 11/17

smallest particle of matter Atoms are the basic building blocks of all matter.

negative charge in an atom found in the electron cloud Electrons play a key role in chemical bonding and electricity.

neutral particle in an atom found in the nucleus Neutrons contribute to the mass of an atom but do not affect its charge.

positive particle in an atom found in the nucleus Protons determine the atomic number and identity of an element.

identifies the atom, # of protons and # of electrons The atomic number is unique to each element.

elements that are the same but have a different number of neutrons Isotopes have the same chemical properties but different masses.

the number of protons and neutrons in an atom= the mass # Mass number is used to identify isotopes.

organized table of the elements in our world The periodic table arranges elements by increasing atomic number.

short-hand version of the elements name; based on the 1st letter or two of the element name or it’s Latin name Chemical symbols are used for easy identification of elements.

rows going across on the table (7) Each period represents a different energy level of electrons.

columns going up and down on the table (18) Elements in the same group often have similar chemical properties.

substance made of two or more elements Compounds have different properties than the individual elements that compose them.

outer shell electrons Valence electrons are involved in chemical bonding.

metal physical property; can be pounded flat or shaped easily Malleability is a key characteristic of metals.

metal physical property; can be coiled into a wire Ductility is important for applications like electrical wiring.

metal physical property; Shiny or reflective Luster is a visual property that helps identify metals.

can conduct electricity under certain conditions (metalloid- Silicon) Semiconductors are crucial for electronic devices.

groups of atoms with an ionic charge Polyatomic ions can participate in ionic bonding.

metal + nonmetal (transfer electrons) Ionic bonds result in the formation of charged ions.

Nonmetal + nonmetal (share electrons) Covalent bonds create molecules through shared electron pairs.

formed when nm + m join and become neutral Molecules are the smallest units of covalent compounds.

equal sharing of electrons occur in a covalent bond Nonpolar molecules do not have charged ends.

unequal sharing of electrons occur in a covalent bond (HCl)- any nonmetal with Hydrogen Polar molecules have distinct positive and negative ends.

Sphere; developed the first atomic theory Dalton’s model was foundational in the understanding of atomic structure.