# Which of the particles make up the atomic mass?

## Which of the particles make up the atomic mass?

The majority of an atoms’ mass comes from the protons and neutrons that make up its nucleus. Electrons are the least massive of an atom’s constituent particles, with a mass of 9.11 x 10-31 kg and a size too small to be measured by current techniques.

Which particles contribute to the atomic number?

The atomic number is the number of protons in an element, while the mass number is the number of protons plus the number of neutrons.

How many particles are in an atom?

three particles
We now know that atoms are made up of three particles: protons, neutrons and electrons — which are composed of even smaller particles, such as quarks. Atoms were created after the Big Bang 13.7 billion years ago. As the hot, dense new universe cooled, conditions became suitable for quarks and electrons to form.

### How do we find atomic mass?

For any given isotope, the sum of the numbers of protons and neutrons in the nucleus is called the mass number. This is because each proton and each neutron weigh one atomic mass unit (amu). By adding together the number of protons and neutrons and multiplying by 1 amu, you can calculate the mass of the atom.

What do you call the element from atomic number 57 71?

The elements from atomic number 57 to 71 are called Lanthanides. They are called lanthanides, since lanthanum is chemically identical to the elements in the sequence. The lanthanides are between Barium and Hafnium.

What is equal to the atomic number?

atomic number, the number of a chemical element in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus. Accordingly, the number of protons, which is always equal to the number of electrons in the neutral atom, is also the atomic number.

#### What is the smallest thing in the universe?

Quarks are among the smallest particles in the universe, and they carry only fractional electric charges. Scientists have a good idea of how quarks make up hadrons, but the properties of individual quarks have been difficult to tease out because they can’t be observed outside of their respective hadrons.

What are the 4 types of atoms?

Different Kinds of Atoms

• Description. Atoms are made of tiny particles called protons, neutrons and electrons.
• Stable. Most atoms are stable.
• Isotopes. Every atom is a chemical element, like hydrogen, iron or chlorine.
• Radioactive. Some atoms have too many neutrons in the nucleus, which makes them unstable.
• Ions.
• Antimatter.

What is an example of atomic mass?

An atomic mass unit is defined as a mass equal to one twelfth the mass of an atom of carbon-12. The mass of any isotope of any element is expressed in relation to the carbon-12 standard. For example, one atom of helium-4 has a mass of 4.0026 amu. An atom of sulfur-32 has a mass of 31.972 amu.

## What is the atomic mass of Na?

22.989769 u
Sodium/Atomic mass

What is the chemical symbol for gold?

Au
Gold/Symbol

What are elements 57 70 called?

lanthanides
The lanthanides are a group of 15 chemically similar elements with atomic numbers 57 through 71, inclusive.