Structures of Matter Test Flashcards
Subatomic Particles
proton, neutron & electron
Proton
Symbol: p+ Location: Inside nucleus Discovered by: Rutherford Charge: Positive Mass: ~1 amu.
Neutron
Symbol: n Location: Inside nucleus Discovered by: Chadwick Charge: Neutral Mass: ~1 amu.
Electron
Symbol: e- Location: Orbit nucleus Discovered by: Thomson Charge: Negative Mass: ~1/2000 amu.
Dalton
1808- Atoms are small solid spheres, different sizes for different elements.
Thomson
1897-Atoms are made of positively charged sphere with negative electrons in the sphere.
Nagaoka
1904-Atoms are made of positive sphere with negative electrons orbiting like the planets orbit the sun.
Rutherford
1911-Atoms are mostly empty space with negative electrons orbiting randomly around the positively charged proton.
Bohr
1913-Atoms are positively charged protons with electrons orbiting nucleus in distinct energy shells.
Modern
1920s to Present-Atoms have positive protons and neutral neutrons in the positively charged nucleus with negative electrons orbiting the nucleus in distinct energy clouds.
Atomic Number
The identity of an element or the number of protons.
Atomic Mass
The average mass of the nucleus of all the atoms of an element. #protons + #neutrons
Electron Shells
First Shell: 2 Second Shell: 8 Third Shell:18 (Z< 21, then 8) Fourth Shell: 32 Fifth Shell: 32 Sixth Shell: 18 Seventh Shell 8
Valence Electrons
The number of electrons in the outermost energy shell of an atom that are held the weakest and transferred or shared in chemical bonds.
Calculating Particles
- # Protons# Protons = Atomic Number
- # Neutrons# Neutrons = Atomic Mass (rounded) - Atomic Number.
note: Atomic Mass=p + n - # ElectronsFor a NEUTRAL atom, #electrons = #protons.
Periodic Table
The arrangement of elements in order of atomic number that shows elements grouped together with other elements of similar properties to form a repeated pattern.
Classifications of elements
metals, metalloids & non-metals
Metals
Good conductors heat/electricity.
Malleable/Ductile. Shiny. Solid @ Room Temperature. Loose Electrons.
Metalloids
Elements with properties of both metals and non-metals.
Non-metals
Poor conductors heat/electricity.
Brittle. Dull. Gas @ Room Temperature. Gain Electrons.
Groups on a periodic table
The vertical columns where the number of valence electrons are the same, so the elements have similar properties.
Periods on a periodic table
The horizontal rows where the number of valence electrons increases by 1, the atomic number increases by 1, and the Period Number equals the number of energy shells.
