What's the matter?
Matter cannot be created or destroyed, but it can change forms.
What is the Law of Conservation of Matter
A proton has this charge.
What is positive?
Rows of the periodic table.
What are periods?
Electrons that are in the hightest energy level of an atom.
What are valence electrons?
The sum of the protons and neutrons in the nudleus of a cell.
What is the mass number?
In the year 450BC, he argued that atoms were the smallest unit of matter.
Who is Democritus?
In Rutherford's atomic model with a nucleus, the positive charge is concentrated here.
What is the center of the atom?
Columns of the periodic table.
What are groups?
An electron must do this in order to move to a higher energy level.
What is gain energy?
Atoms of an element with the same number of protons but different numbers of neutrons.
What is an isotope?
The four elements Aristotle said that all matter is made up of.
What is fire, earth, water, and air?
Protons and electrons have these charges.
What is opposite?
This identifies the number of protons in an atom.
What is the atomic number?
This scientist's model of the atom describes electrons' movement like planets moving around the sun.
Who is Bohr?
Samples of a pure compound always have the same elements in the same mass proportions.
What is the Law of Constant Composition?
The number of these electrons determines an element's chemical properties.
What is valence?
This subatomic particle has a negative charge.
What is electron?
This group of elements on the periodic table are the most reactive.
What are alkali metals (or Group 1A)?
The maximum number of electrons that an atomic orbital can contain.
What is two?
This determines an element's chemical properties.
What is the number of valence electrons?
Almost all of the mass of an atom is found here.
What is nucleus?
His experiments provided evidence that atoms contain negatively charged particles.
Who is JJ Thompson?
The atomic number of an atom which the nucleus contains 17 protons and 18 neutrons.
What is 17?
Thomson's atomic model demonstrated how the negatively charged particles are spread evenly throughout a positively charged mass of matter.
What is The Plum Pudding Model?
This group of elements is the least reactive.
What are the noble gases (Group 8A)?