Atomic Structure
Name the three main particles that make up an atom.
protons, neutrons, electrons
What do we call the table that organizes all known elements?
periodic table
What do we call an atom that has gained or lost electrons?
ion
A substance made of two or more elements chemically combined is called a what?
compound
What is an acid (in terms of ions released in water)?
a substance that releases hydrogen ions (H⁺) in water
What charge does a proton have?
positive
Who was the scientist that developed the periodic table?
Dmitri Mendeleev
What happens to an atom's charge when it loses electrons?
becomes positively charged (cation)
What do we call the symbolic way to show which elements are present in a compound (e.g., H2O
chemical formula
What is a base (in terms of ions released in water)?
a substance that releases hydroxide ions (OH⁻) in water
What charge does a neutron have?
neutral (no charge)
How many periods and groups on the periodic table?
7 Periods
18 Groups
What is it called when atoms share electrons?
covalent bonding
What are the small numbers written after element symbols in a formula called?
subscripts
What scale measures how acidic or basic a substance is?
pH scale
What charge does an electron have?
negative
If an element has an atomic number of 8, how many protons does it have?
8 protons
What is the name of the bond formed when positively and negatively charged ions attract each other?
ionic bond
For the formula CO₂, how many atom(s) of carbon are present?
1 carbon atom
On the pH scale, what does a pH value less than 7 indicate?
an acid
The atomic number of an element tells the number of which particle in the atom?
protons
How many elements on the periodic table?
118 elements
In an ionic bond, are electrons shared or transferred?
transferred — electrons move from one atom to another
For the formula CO₂, how many atom(s) of oxygen are present?
2 oxygen atoms
What does a pH value greater than 7 indicate, and what is a substance with pH of 7 considered? What does a pH less than 7 indicate?
a base; neutral; acid