Bio Adv: Unit 2 - Atoms and Molecules 1 Study Guide

matter

anything made of atoms, has mass, and takes up space

atoms

tiny invisible particles that make up all matter

shells

groups electrons are arranged in

element

a pure substance that consists entirely of one type of atom

atomic mass

the total number of protons and neutrons in the nucleus of an atom

electronegativity

the ability to attract shared electrons toward itself in a chemical bond

protons

positive charge

neutrons

no charge

electrons

negative charge

What is matter?

Anything made of atoms that has mass and takes up space.

What are atoms?

Tiny invisible particles that make up all matter and serve as fundamental building blocks.

What are electron shells?

Groups that electron orbitals are arranged in, where shells farther from the nucleus house higher energy electrons.

What is an element?

A pure substance that consists entirely of one type of atom.

What is atomic mass?

The total number of protons and neutrons in the nucleus of an atom.

What is electronegativity?

The ability of an atom to attract shared electrons toward itself in a chemical bond.

What are protons, and what is their charge and location?

Positively charged (+) subatomic particles located in the nucleus.

What are neutrons, and what is their charge and location?

Subatomic particles with no charge (neutral) located in the nucleus.

What are electrons, and what is their charge and location?

Negatively charged (-) subatomic particles moving around the outside of the nucleus.

What did the ancient Greeks originally think everything in the world was made of?

Four elements: earth, wind, fire, and water.

Which Greek philosopher proposed that everything is made of tiny invisible particles called atoms?

Democritus.

Where are protons and neutrons located, and how are they arranged?

In the nucleus, tightly bound and very densely packed together.

Which subatomic particles comprise almost all the mass in an atom?

Protons and neutrons (which have about the same mass).

Why do electrons stay outside the nucleus despite being attracted to the positively charged nucleus?

Because of the energy of their motion as they fly around the nucleus.

What are electron orbitals?

Blue-green 3D regions that contain electrons, where each orbital can hold a maximum of 2 electrons.

Why are atoms electrically neutral?

Because they have equal numbers of positively charged protons and negatively charged electrons, balancing the overall charge.

What determines the identity of an element?

The number of protons in the atom's nucleus.

How many known elements are there on the periodic table?

118 known elements.

What does the atomic number of an element represent?

The number of protons in an atom (which also equals the number of electrons in a neutral atom).

How are elements arranged on the periodic table?

From left to right according to increasing atomic number.

What would happen to a carbon atom if it gained a proton?

It would no longer be carbon and would become nitrogen instead.

Where is the atomic mass located on a periodic table element card?

At the bottom of the element entry.

How do you calculate the number of neutrons in an atom?

Subtract the atomic number from the rounded atomic mass number (Neutrons = Mass Number - Atomic Number).

If Sodium has an atomic number of 11 and an atomic mass of 22.9898, how many neutrons does it have?

12 neutrons (23 - 11 = 12).

What are isotopes?

Atoms of the same element that have the same number of protons but differ in the number of neutrons.

How are different isotopes of an element identified?

By their atomic mass (e.g., Carbon-12, Carbon-13, Carbon-14).

What is the general trend for electronegativity across a period (left to right)?

Electronegativity increases from left to right.

What is the general trend for electronegativity down a group (top to bottom)?

Electronegativity decreases from top to bottom.