Periodic Table Basics
What do periods on the periodic table represent?
The number of electron shells an element has.
What is the charge of a proton?
Positive
Who developed the "plum pudding" model of the atom?
Thomson
What are elements in the same group said to have in common?
Similar chemical properties.
What is an independent variable in an experiment?
The variable that is changed on purpose.
Which group on the periodic table is known as the Noble Gases?
Group 18
What 2 subatomic particles are found in the nucleus of an atom?
Protons and Neutrons
Which scientist proposed that atoms are mostly empty space?
Rutherford
What is a metalloid?
An element that has both metal and non-metal properties.
What is a control group?
The group or condition that receives the "normal" treatment.
What is common among elements in the same group?
They have the same number of valence electrons.
What is the atomic number of an element equal to?
The number of protons
Describe Bohr’s model of the atom.
Electrons orbit the nucleus like planets around the sun
What is a key characteristic of non-metals?
They are poor conductors of heat and electricity.
What must stay constant in a controlled experiment?
All variables except the independent variable.
What is the name of Group 1 elements, and why are they very reactive?
Alkali metals, because they have only one valence electron.
How is atomic mass calculated?
By adding the number of protons and neutrons.
What did Dalton believe atoms looked like?
Solid spheres, like a marble or pool ball.
Name a property of metals.
Metals are malleable and good conductors of heat and electricity.
What is an inference?
Using observations to make a conclusion about what is happening.
How are the elements on the periodic table arranged?
By increasing atomic number.
Where are electrons located in an atom?
In the electron cloud outside the nucleus.
What is the modern theory of the atom's structure?
Electrons move quickly in a cloud around a small nucleus that holds most of the atom's mass.
Why don’t Noble Gases react with other elements?
They have a full outer shell of 8 valence electrons.
What is a hypothesis?
A prediction of what will happen in an experiment based on prior knowledge.