Question

2.3 atomic structure and symbolism
table 1. parts of an atom

particle	charge (c)	unit charge	mass (g)	mass (amu)
proton	1.602 × 10⁻¹⁹	1+	1.673 × 10⁻²⁴	1.0072
neutron	0	0	1.676 × 10⁻²⁴	1.0087

note: conversion from amu to grams: 1 amu = 1.661 × 10⁻²⁴ g

define:

atomic number (z)

mass number (a)

ion

cation

anion

table 2. elements you need to know this semester

li	be											b	c	n	o	f	ne
na	mg											al	si	p	s	cl	ar
k	ca	sc	ti	v	cr	mn	fe	co	ni	cu	zn	ga		as	se	br	kr
rb	sr		zr										sn	sb		i	xe
cs	ba			w					pt	au	hg		pb	bi
															ts

Explanation:

1. Atomic number (Z): It is a unique identifier for each element, equal to the number of protons in the nucleus of an atom of that element. In a neutral atom, it also matches the number of electrons.
2. Mass number (A): This is the total number of protons and neutrons (collectively called nucleons) in the nucleus of a single atom. It is a whole number approximation of an atom's mass.
3. Ion: An atom or molecule that has gained or lost one or more valence electrons, resulting in a net positive or negative electrical charge (no longer electrically neutral).
4. Cation: A positively charged ion formed when an atom or molecule loses one or more valence electrons, leaving more protons than electrons.
5. Anion: A negatively charged ion formed when an atom or molecule gains one or more valence electrons, leaving more electrons than protons.

Answer:

1. Atomic number (Z): The number of protons in an atom's nucleus; defines an element.
2. Mass number (A): The total number of protons + neutrons in an atom's nucleus.
3. Ion: A charged atom/molecule from electron gain/loss.
4. Cation: Positively charged ion from electron loss.
5. Anion: Negatively charged ion from electron gain.