Introduction to ions | High school chemistry | Khan Academy

Summary

The video introduces the concept of ions in chemistry, starting with a review of elements, particularly carbon and boron, and how ions form due to an imbalance of protons and electrons. It explains that an atom becomes an ion when it has a net charge, with more or fewer electrons than protons. The video uses the example of platinum, demonstrating how to calculate protons, neutrons, and the overall charge of an ion. The terms "cation" and "anion" are described, referring to positive and negative ions, respectively.

Highlights

• The basics of ions start with understanding neutral atoms and element definitions. 🧪
• Ions are characterized by an imbalance of protons and electrons, leading to a net charge. ⚛️
• Common terms: positive ion (cation) and negative ion (anion) are essential for chemistry lingo! 💬
• Example with platinum: Calculating protons, neutrons, and identifying the ion's charge. 🔍
• Transition from atoms to ions occurs with changes in electron count, a foundational chemistry concept. 💡

Key Takeaways

• Understanding ions starts with knowing elements: protons define the element, and electrons balance the charge. 🧑‍🔬
• An ion forms when the numbers of protons and electrons are unbalanced, leading to a net charge. ⚖️
• Platinum example: 78 protons and 74 electrons results in a +4 cation charge. 💡
• Positive ions are cations, and negative ions are anions. Remember these cool names! 🧐
• Mass number equals the sum of protons and neutrons, a crucial concept in identifying ions. 🧮

Overview

Delve into the intriguing world of ions with this Khan Academy lesson that highlights the differences between neutral atoms and ions. Understanding the number of protons, neutrons, and electrons in an element like carbon or boron sets the stage for grasping how ions form when these counts become unbalanced. Whether losing or gaining electrons, this imbalance transforms a neutral atom into a charged ion.

Using real-world examples, such as platinum, the video breaks down how to determine the charge of an ion. For instance, platinum has 78 protons, and when it has 74 electrons, it results in a +4 charge, classifying it as a cation. This clear demonstration reinforces the basic principle where protons define the element, and discrepancies in proton-electron counts lead to ions.

Learn the jargon of chemistry with terms like cation, which refers to a positive ion, and anion, which refers to a negative one. As these terms are unveiled through discussions about balancing mass numbers with protons and neutrons, students are equipped with knowledge crucial for mastering high school chemistry concepts.

Chapters

• 00:00 - 03:00: Introduction to Elements and Ions The chapter "Introduction to Elements and Ions" begins with an acknowledgment of the speaker's recent deviated septum surgery, slightly affecting the delivery. The focus of the chapter is to introduce the concept of an ion. Before delving into ions, the chapter discusses elements, using carbon as an example. It highlights that an element, such as carbon, has specific properties, such as the atomic number, which in carbon's case is 6. This sets the foundation for understanding the nature of ions.
• 03:00 - 07:00: Example Question: Platinum Ion The chapter discusses the structure of carbon, focusing on its protons and electrons. It highlights that a neutral carbon atom contains six protons and six electrons, resulting in an equal number of positive and negative charges. The concept of carbon ions is introduced, noting that they aren't typical, and explains that ions are formed when the number of protons and electrons do not equal.
• 07:00 - 10:00: Understanding Neutral vs. Ion The chapter discusses the concept of neutral atoms versus ions, using the example of an element with differing numbers of protons and electrons. It explains that while the number of protons determines the element (e.g., carbon with 6 protons), having a different number of electrons (e.g., 5 electrons) results in a positive charge, making the atom an ion.

Introduction to ions | High school chemistry | Khan Academy Transcription

• 00:00 - 00:30 so my apologies i just had a deviated septum surgery yesterday but what we're going to talk about in this video is the notion of an ion so before we talk about iods we're just going to talk about the idea of an element for example if i have carbon carbon is an element let's say i have one atom of carbon what do we know about that one atom of carbon well by definition an atom of carbon has six
• 00:30 - 01:00 protons so it's going to have six protons and if it is neutral carbon it is going to have the same number of electrons it is going to have six electrons and that's what makes it neutral you have the six positive charges and the six negative charges now you could have a carbon ion although they aren't that typical the way you get an ion is if you don't have an equal
• 01:00 - 01:30 amount of protons and electrons so for example if you had 6 protons and five electrons what would that be well we still have six protons and remember protons are what define what element we're dealing with so we're still dealing with carbon but now we have one more positive charge then we have a negative charge so this
• 01:30 - 02:00 will be carbon with you could write it as a one plus charge like that or you could even write it like this and this you would just view as a carbon atom this you would now call an ion because it has that net charge it has a different number of protons and electrons what if you were to go the other way around what if you were to have five protons five protons and six electrons
• 02:00 - 02:30 what would this be well remember protons define what element you're dealing with so now if you look at what element has five protons we're dealing with boron so this is going to be boron neutral boron would have five protons and five electrons but this one has one extra electron so it has one extra negative charge so you could write it like this one minus or you could just say it has a negative
• 02:30 - 03:00 charge so this is a boron ion right over here as soon as you have an imbalance between protons and electrons you no longer would call it an atom you would call it an actual ion now let's do an example question dealing with this so our question tells us our question our question tells us and adam
• 03:00 - 03:30 an atom of platinum has a mass number of 195 so let's just look up platinum on our periodic table platinum is sitting right over here if you could see it so an atom of platinum has a mass number of 195 and 195 looks pretty close to that atomic mass we have listed there and it contains 74 electrodes
• 03:30 - 04:00 74 electrons how many protons and neutrons does it contain and what is its charge all right so let's think about this a little bit so we're dealing with platinum so by definition platinum has 78 protons so we know that it has 78 78 protons they they're telling us it has 74 electrons 74
• 04:00 - 04:30 electrons elec electrons so just from that we see we have four more protons than electrons so you have you're going gonna have a positive four charge four more of the positive things that you have of the elec of the negative things so you could write this as platinum with a plus four charge this is a platinum ion a positive platinum ion the general term
• 04:30 - 05:00 when we're talking about a positive ion we're talking about a cation that is a positive positive ion up there when we talked about boron being negative a negative ion that is an anion this is just to get ourselves used to use used to some of the terminology but we're not done answering the question they say an atom of platinum has a mass
• 05:00 - 05:30 number of 195 and contained 74 electrons how many protons and neutrons does it contain and what is its charge we figured out its charge we know the protons by definition platinum has 78 protons but what about its neutrons well protons plus neutrons is going to be equal to our mass number it's going to be equal to 195.
• 05:30 - 06:00 so we have 78 protons plus i'll say n for neutrons is equal to 195 subtract 78 from both sides and what do you get the number of neutrons is equal to 1 100 let's see if i subtract 70 i'll get 100 and i'll get 125 minus 8 i have 117 neutrons
• 06:00 - 06:30 so 117 neutrons and we're done but the big idea is and we say atom when we have the same number of electrons and protons that's when we are neutral but as soon as we become non-neutral we have either more electrons or more protons and this is true of an atom or molecule we will then call it an ion and if you want to be a little bit more specific a positive ion is called a
• 06:30 - 07:00 cation and a negative ion is called an anion