Chemistry Definitions Grade 9 Flashcards
What are Alkali Metals
Found in Group 1, they are soft, silver, grey metals that are reactive
What are Alkaline Earth Metals
Found in Group 2, they are silver, grey, solids that are harder then Alkali Metals and less reactive
Atom
An atom is a particle that has nucleus of protons and neutrons surrounded by electrons
Atomic Number
A number on an element symbol that signifies how many protons there are in that element
Atomic Mass number
A number on an element symbol that signifies the amount of protons and neutrons averaged
Bohr
Bohr changed Rutherfords diagram by having electrons “Orbit” around the nucleus at set “Energy Levels,” in this idea electrons could not orbit between the Energy levels
Chemical Change
A chemical change occurs when a substance combines with another substance to form a new substance
Chemical Formula
An expression that shows the elements in a compound and the relative proportions of those elements.
Chemical Property
Describes the “ability” of a substance to undergo a specific chemical change
Chemical Symbol
A short form of chemical elements, usually from the Latin alphabet (ex. Cu, Copper)
Compound
A pure substance containing 2 or more elements that are chemically joined, is not on the periodic table
Covalent Bond
2 atoms are bonded by sharing an electron in one of its orbits
Electron
A negatively charged subatomic particle that orbits nuclei
Element
A substance whose atoms all have the same atomic number
Group/Family
The columns on the periodic table that dictate how many valence electrons there are in an element, left-right, 1-18
Halogens
The 6 elements in Group 17 halogens are the most reactive non-metals and are usually found as compounds not elements
(F and Cl are gasses, Br is a brown liquid, I is a violet solid, At is radioactive)
Matter
Anything that has mass and takes up space
Metalloids
Along the staircase line, they have properties of metals and non-metals, some conductive, some not
Metals
On the left side of the periodic table they have a metallic lustre, conductive of electricity, solid, and ductile
Molecule
A group of 2 or more atoms held together by a chemical bond
Neutron
A subatomic particle with a neutral charge in the nucleus
Noble Gases
Found in Group 18, they are odourless, colourless, stable, valence shell is full so does not need more electrons to become stable
Non-metals
Found on the right side of the periodic table they are gases, powdery solids, brittle, dull and poor conductors of electricity(generally)
Period
The rows of the periodic table they signify the amount of orbits/energy levels of an atom
Periodic table
A table of elements arranged by atomic number, valence electrons and orbits
Physical change
The particles in the substance remain unchanged and the number of particles remain unchanged
Physical Property
A characteristic of a substance that can be observed without changing the substance
Proton
A positively charged subatomic particle that is found in the nucleus of an atom
Pure substance
A substance where all molecules are exactly the same
Rutherford
Realized positive charge was localized in the nucleus of an atom, but did not explain why electrons remain in orbit around the nucleus
Standard atomic notation
An easier method to write an element with all necessary information, N and P combined top left, Atomic symbol middle, Protons/Electrons bottom left
Subscript
A number written in the lower right corner behind the symbol of an element, used to indicate the number of atoms of any given element
Valence electrons
The electrons in the furthest orbit from the nucleus
Valence shell
The furthest orbit with electrons from the nucleus
