Who first proposed that everything in the world was made up of tiny particles?

• Aristotle
• Democritus
• Plato
• Socrates

Tags

NGSS.MS-PS1-1

Democritus called the tiniest particles of matter "atomos", which is Greek for _____

• empty space
• invisible
• very small
• indivisible

Tags

NGSS.MS-PS1-1

Isotopes have the same number of ____, but different number of ____.

• neutrons; protons

• protons; electrons

• protons; neutrons

• electrons; protons

What is the atom's nucleus made of?

• protons

• electrons

• neutrons

• ions

Atoms of the same element that have different numbers of neutrons are called_________

• molecules

• ions

• protons

• isotopes

Which particles determine the atomic number of an element?

• protons only

• protons and neutrons

• electrons

• protons and electrons

Beryllium is in GROUP 2 because it

• is a metal

• is a gas

• has 2 valence electrons

• has 2 energy levels

Atoms of elements in the same GROUP of the periodic table share the same

• number of energy levels

• number of valence electrons

• atomic numbers

• atomic masses

An element with 4 protons, 5 neutrons, and 4 electrons has a mass number of _______

• 7

• 9

• 13

• 14

Tags

NGSS.MS-PS1-1

The total number of neutrons of any atom is equal to the

• mass of the atom

• mass number minus the atomic number

• atomic number of the atom