Question

1. how would you write the element symbol for this element?

key concept checkpoint

1. which number determines the identity of an atom? (which element it is)
2. does the number of neutrons affect an atom’s identity? explain your answer.
3. does the number of electrons affect an atom’s identity? explain your answer.
4. do the number of protons, neutrons, and electrons always equal each other? explain.
5. where do you find protons, neutrons, and electrons in an atom?

pen challenge! (group work)
place your colored beads back into the cup and return the materials used back to mrs. rector.
mrs. rector will give you a set of mystery samples. your job is to identify the number of protons, neutrons, and electrons in the sample and identify the element. once you identify the element you must determine if the sample is a neutral atom, an ion, or an isotope. fill in the chart below as you work through the mystery samples.
sample # # of p # of e # of n atomic number mass number element atom, ion, or isotope?

Explanation:

1. The identity of an atom is determined by the number of protons, which is the atomic number.
2. Neutrons affect mass but not the element's identity; isotopes have different neutrons but same element.
3. Electrons can be gained/lost (forming ions) without changing the element's identity.
4. Protons equal electrons in neutral atoms, but neutrons often differ; they are not always equal.
5. Protons and neutrons are in the nucleus; electrons are in the electron cloud surrounding the nucleus.

Answer:

1. Atomic number (number of protons)
2. No; neutrons affect mass, not identity (isotopes are same element).
3. No; electrons can vary (ions) without changing the element.
4. No; protons = electrons (neutral), neutrons often differ.
5. Protons/neutrons: nucleus; electrons: electron cloud.