Unit B - Section 2 Flashcards
Atoms
Each element is composed of a particle called an atom
Dalton’s theory
Suggested that matter was made up of elements
Electrons
Negatively charged particles
Nucleus
A tiny positively charged centre
Protons
Positively charged particles
Neutrons
Neither positively or negatively charged
Bohr’s theory
Believed that electrons jump between these shells by gaining or losing energy. Bohr also stated that electrons moved in specific circular orbits
Atomic mass
Is the mass of one atom of an element
Each horizontal row is called a
Period (1-7)
Each vertical column forms a
Group or a family of elements (1-18)
Atomic number
Shows how many protons there r in the element
Metals
Green box represents metals (metals r shiny malleable and ductile) they also conduct electricity
Metalloids
Purple box represents metalloids (metalloids have both metallic and non metallic properties)
Non metals
The orange box represents non metals (can be a solid or a gas. Non metals r dull brittle elements. Do not conduct electricity)
Alkali metals
The most reactive of all the metals (they r group one elements) they react when composed to air or water
Alkaline earth metals
React when composed to air and water. The reactivity isn’t as strong as alkali metals group 2 in the periodic table
Halogens
Halogens is group 17. They r the most reactive non metals
Noble gases
Noble gases is group 18. They r the nose stable and unreactive elements
Atomic mass unit
Atomic mass us measured by atomic mass unit (amu).
Mass number represents…
The number of protons and neutrons in an atom
Groups 3-12 r called…
Transitional metals
