Definitions
The sum of protons and neutrons in the nucleus of a cell.
This is the name of the elements that share similar properties.
What is groups or families?
This scientist coined the phrase "atom" from the Greek word "atomos."
Who is Democritus?
Almost all of the mass of an atom is found here.
Where is the nucleus?
Alkali metals only exist in this form in nature.
What is compounds?
The number of protons in an atom.
What is the Atomic Number?
The rows, or periods, of a periodic table signify these two patterns.
What is the atomic mass increases and the properties of the atoms change?
These two laws were the foundation of Dalton's atomic theory.
What is the Law of Conservation of Mass and the Law of Constant Composition?
This type of particle is found outside the nucleus with a negative charge.
What is an electron?
Reactivity is greater in lower groups or higher groups of Alkali metals?
What is lower groups?
Atoms of an element with the same number of protons but different numbers of neutrons.
What is an Isotope?
Each element is defined by this in the periodic table.
What is the atomic number?
This scientist discovered that all matter has negatively charged particles.
Who is JJ Thomson?
This is the maximum number of electrons that an atomic orbital can contain.
What is 16?
This group contains aluminum, gallium, indium, boron, thallium, and nihonium.
What is the boron group?
Electrons that are in the highest energy level of an atom.
What are Valence Electrons?
The number of the group matches this number.
What is the number of valence electrons?
Who is Ernest Rutherford?
If an atom of an element has a mass number of 32 and 15 neutrons in its nucleus, this is its atomic number?
What is 17?
This group contains all non-metals.
What is the halogen group?
Matter cannot be created or destroyed, but it can change forms.
What is the Law of Constant Composition?
This is why elements are placed in groups 1A-8A.
What is because these groups contain the most important elements for life. They are the most naturally occurring and comprise about 80% of the Earth's crust.
This scientist hypothesized that electrons moved around the nucleus like planets orbiting the sun. His theory was later improved by describing it as more of an electron cloud.
Who is Niels Bohr?
This must happen for an electron to move to a higher energy level.
What is the electron must gain energy?
This group does not react with other elements.
What are the Noble gases?