The _________________ is defined as the smallest unit of matter that can still be considered an element.

Together, the protons and neutrons make up almost all the __________________________ of an atom.

Surrounding the nucleus is a cloud-like region of moving _________________________.

What are the small, positively charged particles that are found in the nucleus of an atom?

An atom with the same number of protons and a different number of neutrons from other atoms of the same element is called a/an

Scientists have to use models to study ___________ because they are so small.

______________ is a small particle in the nucleus of an atom, with no electrical charge

What is a tiny, negatively charged particle that moves around the outside of the nucleus of an atom?

The _______________ is a region of an atom in which electrons of the same energy are likely to be found

______________is the number of protons in the nucleus of an atom, this defines the element:

The number of the protons and neutrons in the atom is known as the:

Together, the protons and _____________ make up almost all the mass of an atom

AMU stands for:

Which model describes:

positive charged nucleus and negative charges throughout, like seeds in a watermelon

Which model assigns two-dimensional orbit of

(-) electrons around a (+) nucleus of protons and also showed electron shells or levels for the first time?

Negatively charged particles in an atom are known as:

Bohr's model of the atom consisted of a central ________ surrounded by electrons moving in a specific orbit.

A particle with NO charge is a:

The sum of a protons and neutrons in a nucleus of an atom is called the:

An element's identity is known as its:

Scientists use models to study atoms because atoms are:

A classification system where elements are organized according to atomic number:

A pure substance that can't be broken down into any other substance:

A group of two or more atoms held together by chemical bonds: